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This is, produced by makeinfo version 5.2 from libc.texinfo.
This file documents the GNU C Library.
This is 'The GNU C Library Reference Manual', for version 2.19
Copyright (C) 1993-2014 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Free Software Needs Free Documentation" and
"GNU Lesser General Public License", the Front-Cover texts being "A GNU
Manual", and with the Back-Cover Texts as in (a) below. A copy of the
license is included in the section entitled "GNU Free Documentation
(a) The FSF's Back-Cover Text is: "You have the freedom to copy and
modify this GNU manual. Buying copies from the FSF supports it in
developing GNU and promoting software freedom."
INFO-DIR-SECTION Software libraries
* Libc: (libc). C library.
INFO-DIR-SECTION GNU C library functions and macros
* ALTWERASE: (libc)Local Modes.
* ARGP_ERR_UNKNOWN: (libc)Argp Parser Functions.
* ARG_MAX: (libc)General Limits.
* BC_BASE_MAX: (libc)Utility Limits.
* BC_DIM_MAX: (libc)Utility Limits.
* BC_SCALE_MAX: (libc)Utility Limits.
* BC_STRING_MAX: (libc)Utility Limits.
* BRKINT: (libc)Input Modes.
* BUFSIZ: (libc)Controlling Buffering.
* CCTS_OFLOW: (libc)Control Modes.
* CHILD_MAX: (libc)General Limits.
* CIGNORE: (libc)Control Modes.
* CLK_TCK: (libc)Processor Time.
* CLOCAL: (libc)Control Modes.
* CLOCKS_PER_SEC: (libc)CPU Time.
* COLL_WEIGHTS_MAX: (libc)Utility Limits.
* CPU_CLR: (libc)CPU Affinity.
* CPU_ISSET: (libc)CPU Affinity.
* CPU_SET: (libc)CPU Affinity.
* CPU_SETSIZE: (libc)CPU Affinity.
* CPU_ZERO: (libc)CPU Affinity.
* CREAD: (libc)Control Modes.
* CRTS_IFLOW: (libc)Control Modes.
* CS5: (libc)Control Modes.
* CS6: (libc)Control Modes.
* CS7: (libc)Control Modes.
* CS8: (libc)Control Modes.
* CSIZE: (libc)Control Modes.
* CSTOPB: (libc)Control Modes.
* DES_FAILED: (libc)DES Encryption.
* DTTOIF: (libc)Directory Entries.
* E2BIG: (libc)Error Codes.
* EACCES: (libc)Error Codes.
* EADDRINUSE: (libc)Error Codes.
* EADDRNOTAVAIL: (libc)Error Codes.
* EADV: (libc)Error Codes.
* EAFNOSUPPORT: (libc)Error Codes.
* EAGAIN: (libc)Error Codes.
* EALREADY: (libc)Error Codes.
* EAUTH: (libc)Error Codes.
* EBACKGROUND: (libc)Error Codes.
* EBADE: (libc)Error Codes.
* EBADF: (libc)Error Codes.
* EBADFD: (libc)Error Codes.
* EBADMSG: (libc)Error Codes.
* EBADR: (libc)Error Codes.
* EBADRPC: (libc)Error Codes.
* EBADRQC: (libc)Error Codes.
* EBADSLT: (libc)Error Codes.
* EBFONT: (libc)Error Codes.
* EBUSY: (libc)Error Codes.
* ECANCELED: (libc)Error Codes.
* ECHILD: (libc)Error Codes.
* ECHO: (libc)Local Modes.
* ECHOCTL: (libc)Local Modes.
* ECHOE: (libc)Local Modes.
* ECHOK: (libc)Local Modes.
* ECHOKE: (libc)Local Modes.
* ECHONL: (libc)Local Modes.
* ECHOPRT: (libc)Local Modes.
* ECHRNG: (libc)Error Codes.
* ECOMM: (libc)Error Codes.
* ECONNABORTED: (libc)Error Codes.
* ECONNREFUSED: (libc)Error Codes.
* ECONNRESET: (libc)Error Codes.
* ED: (libc)Error Codes.
* EDEADLK: (libc)Error Codes.
* EDEADLOCK: (libc)Error Codes.
* EDESTADDRREQ: (libc)Error Codes.
* EDIED: (libc)Error Codes.
* EDOM: (libc)Error Codes.
* EDOTDOT: (libc)Error Codes.
* EDQUOT: (libc)Error Codes.
* EEXIST: (libc)Error Codes.
* EFAULT: (libc)Error Codes.
* EFBIG: (libc)Error Codes.
* EFTYPE: (libc)Error Codes.
* EGRATUITOUS: (libc)Error Codes.
* EGREGIOUS: (libc)Error Codes.
* EHOSTDOWN: (libc)Error Codes.
* EHOSTUNREACH: (libc)Error Codes.
* EHWPOISON: (libc)Error Codes.
* EIDRM: (libc)Error Codes.
* EIEIO: (libc)Error Codes.
* EILSEQ: (libc)Error Codes.
* EINPROGRESS: (libc)Error Codes.
* EINTR: (libc)Error Codes.
* EINVAL: (libc)Error Codes.
* EIO: (libc)Error Codes.
* EISCONN: (libc)Error Codes.
* EISDIR: (libc)Error Codes.
* EISNAM: (libc)Error Codes.
* EKEYEXPIRED: (libc)Error Codes.
* EKEYREJECTED: (libc)Error Codes.
* EKEYREVOKED: (libc)Error Codes.
* EL2HLT: (libc)Error Codes.
* EL2NSYNC: (libc)Error Codes.
* EL3HLT: (libc)Error Codes.
* EL3RST: (libc)Error Codes.
* ELIBACC: (libc)Error Codes.
* ELIBBAD: (libc)Error Codes.
* ELIBEXEC: (libc)Error Codes.
* ELIBMAX: (libc)Error Codes.
* ELIBSCN: (libc)Error Codes.
* ELNRNG: (libc)Error Codes.
* ELOOP: (libc)Error Codes.
* EMEDIUMTYPE: (libc)Error Codes.
* EMFILE: (libc)Error Codes.
* EMLINK: (libc)Error Codes.
* EMSGSIZE: (libc)Error Codes.
* EMULTIHOP: (libc)Error Codes.
* ENAMETOOLONG: (libc)Error Codes.
* ENAVAIL: (libc)Error Codes.
* ENEEDAUTH: (libc)Error Codes.
* ENETDOWN: (libc)Error Codes.
* ENETRESET: (libc)Error Codes.
* ENETUNREACH: (libc)Error Codes.
* ENFILE: (libc)Error Codes.
* ENOANO: (libc)Error Codes.
* ENOBUFS: (libc)Error Codes.
* ENOCSI: (libc)Error Codes.
* ENODATA: (libc)Error Codes.
* ENODEV: (libc)Error Codes.
* ENOENT: (libc)Error Codes.
* ENOEXEC: (libc)Error Codes.
* ENOKEY: (libc)Error Codes.
* ENOLCK: (libc)Error Codes.
* ENOLINK: (libc)Error Codes.
* ENOMEDIUM: (libc)Error Codes.
* ENOMEM: (libc)Error Codes.
* ENOMSG: (libc)Error Codes.
* ENONET: (libc)Error Codes.
* ENOPKG: (libc)Error Codes.
* ENOPROTOOPT: (libc)Error Codes.
* ENOSPC: (libc)Error Codes.
* ENOSR: (libc)Error Codes.
* ENOSTR: (libc)Error Codes.
* ENOSYS: (libc)Error Codes.
* ENOTBLK: (libc)Error Codes.
* ENOTCONN: (libc)Error Codes.
* ENOTDIR: (libc)Error Codes.
* ENOTEMPTY: (libc)Error Codes.
* ENOTNAM: (libc)Error Codes.
* ENOTRECOVERABLE: (libc)Error Codes.
* ENOTSOCK: (libc)Error Codes.
* ENOTSUP: (libc)Error Codes.
* ENOTTY: (libc)Error Codes.
* ENOTUNIQ: (libc)Error Codes.
* ENXIO: (libc)Error Codes.
* EOF: (libc)EOF and Errors.
* EOPNOTSUPP: (libc)Error Codes.
* EOVERFLOW: (libc)Error Codes.
* EOWNERDEAD: (libc)Error Codes.
* EPERM: (libc)Error Codes.
* EPFNOSUPPORT: (libc)Error Codes.
* EPIPE: (libc)Error Codes.
* EPROCLIM: (libc)Error Codes.
* EPROCUNAVAIL: (libc)Error Codes.
* EPROGMISMATCH: (libc)Error Codes.
* EPROGUNAVAIL: (libc)Error Codes.
* EPROTO: (libc)Error Codes.
* EPROTONOSUPPORT: (libc)Error Codes.
* EPROTOTYPE: (libc)Error Codes.
* EQUIV_CLASS_MAX: (libc)Utility Limits.
* ERANGE: (libc)Error Codes.
* EREMCHG: (libc)Error Codes.
* EREMOTE: (libc)Error Codes.
* EREMOTEIO: (libc)Error Codes.
* ERESTART: (libc)Error Codes.
* ERFKILL: (libc)Error Codes.
* EROFS: (libc)Error Codes.
* ERPCMISMATCH: (libc)Error Codes.
* ESHUTDOWN: (libc)Error Codes.
* ESOCKTNOSUPPORT: (libc)Error Codes.
* ESPIPE: (libc)Error Codes.
* ESRCH: (libc)Error Codes.
* ESRMNT: (libc)Error Codes.
* ESTALE: (libc)Error Codes.
* ESTRPIPE: (libc)Error Codes.
* ETIME: (libc)Error Codes.
* ETIMEDOUT: (libc)Error Codes.
* ETOOMANYREFS: (libc)Error Codes.
* ETXTBSY: (libc)Error Codes.
* EUCLEAN: (libc)Error Codes.
* EUNATCH: (libc)Error Codes.
* EUSERS: (libc)Error Codes.
* EWOULDBLOCK: (libc)Error Codes.
* EXDEV: (libc)Error Codes.
* EXFULL: (libc)Error Codes.
* EXIT_FAILURE: (libc)Exit Status.
* EXIT_SUCCESS: (libc)Exit Status.
* EXPR_NEST_MAX: (libc)Utility Limits.
* FD_CLOEXEC: (libc)Descriptor Flags.
* FD_CLR: (libc)Waiting for I/O.
* FD_ISSET: (libc)Waiting for I/O.
* FD_SET: (libc)Waiting for I/O.
* FD_SETSIZE: (libc)Waiting for I/O.
* FD_ZERO: (libc)Waiting for I/O.
* FILENAME_MAX: (libc)Limits for Files.
* FLUSHO: (libc)Local Modes.
* FOPEN_MAX: (libc)Opening Streams.
* FP_ILOGB0: (libc)Exponents and Logarithms.
* FP_ILOGBNAN: (libc)Exponents and Logarithms.
* F_DUPFD: (libc)Duplicating Descriptors.
* F_GETFD: (libc)Descriptor Flags.
* F_GETFL: (libc)Getting File Status Flags.
* F_GETLK: (libc)File Locks.
* F_GETOWN: (libc)Interrupt Input.
* F_OK: (libc)Testing File Access.
* F_SETFD: (libc)Descriptor Flags.
* F_SETFL: (libc)Getting File Status Flags.
* F_SETLK: (libc)File Locks.
* F_SETLKW: (libc)File Locks.
* F_SETOWN: (libc)Interrupt Input.
* HUGE_VAL: (libc)Math Error Reporting.
* HUGE_VALF: (libc)Math Error Reporting.
* HUGE_VALL: (libc)Math Error Reporting.
* HUPCL: (libc)Control Modes.
* I: (libc)Complex Numbers.
* ICANON: (libc)Local Modes.
* ICRNL: (libc)Input Modes.
* IEXTEN: (libc)Local Modes.
* IFNAMSIZ: (libc)Interface Naming.
* IFTODT: (libc)Directory Entries.
* IGNBRK: (libc)Input Modes.
* IGNCR: (libc)Input Modes.
* IGNPAR: (libc)Input Modes.
* IMAXBEL: (libc)Input Modes.
* INADDR_ANY: (libc)Host Address Data Type.
* INADDR_BROADCAST: (libc)Host Address Data Type.
* INADDR_LOOPBACK: (libc)Host Address Data Type.
* INADDR_NONE: (libc)Host Address Data Type.
* INFINITY: (libc)Infinity and NaN.
* INLCR: (libc)Input Modes.
* INPCK: (libc)Input Modes.
* IPPORT_RESERVED: (libc)Ports.
* ISIG: (libc)Local Modes.
* ISTRIP: (libc)Input Modes.
* IXANY: (libc)Input Modes.
* IXOFF: (libc)Input Modes.
* IXON: (libc)Input Modes.
* LINE_MAX: (libc)Utility Limits.
* LINK_MAX: (libc)Limits for Files.
* L_ctermid: (libc)Identifying the Terminal.
* L_cuserid: (libc)Who Logged In.
* L_tmpnam: (libc)Temporary Files.
* MAXNAMLEN: (libc)Limits for Files.
* MAXSYMLINKS: (libc)Symbolic Links.
* MAX_CANON: (libc)Limits for Files.
* MAX_INPUT: (libc)Limits for Files.
* MB_CUR_MAX: (libc)Selecting the Conversion.
* MB_LEN_MAX: (libc)Selecting the Conversion.
* MDMBUF: (libc)Control Modes.
* MSG_DONTROUTE: (libc)Socket Data Options.
* MSG_OOB: (libc)Socket Data Options.
* MSG_PEEK: (libc)Socket Data Options.
* NAME_MAX: (libc)Limits for Files.
* NAN: (libc)Infinity and NaN.
* NCCS: (libc)Mode Data Types.
* NGROUPS_MAX: (libc)General Limits.
* NOFLSH: (libc)Local Modes.
* NOKERNINFO: (libc)Local Modes.
* NSIG: (libc)Standard Signals.
* NULL: (libc)Null Pointer Constant.
* ONLCR: (libc)Output Modes.
* ONOEOT: (libc)Output Modes.
* OPEN_MAX: (libc)General Limits.
* OPOST: (libc)Output Modes.
* OXTABS: (libc)Output Modes.
* O_ACCMODE: (libc)Access Modes.
* O_APPEND: (libc)Operating Modes.
* O_ASYNC: (libc)Operating Modes.
* O_CREAT: (libc)Open-time Flags.
* O_EXCL: (libc)Open-time Flags.
* O_EXEC: (libc)Access Modes.
* O_EXLOCK: (libc)Open-time Flags.
* O_FSYNC: (libc)Operating Modes.
* O_IGNORE_CTTY: (libc)Open-time Flags.
* O_NDELAY: (libc)Operating Modes.
* O_NOATIME: (libc)Operating Modes.
* O_NOCTTY: (libc)Open-time Flags.
* O_NOLINK: (libc)Open-time Flags.
* O_NONBLOCK: (libc)Open-time Flags.
* O_NONBLOCK: (libc)Operating Modes.
* O_NOTRANS: (libc)Open-time Flags.
* O_RDONLY: (libc)Access Modes.
* O_RDWR: (libc)Access Modes.
* O_READ: (libc)Access Modes.
* O_SHLOCK: (libc)Open-time Flags.
* O_SYNC: (libc)Operating Modes.
* O_TRUNC: (libc)Open-time Flags.
* O_WRITE: (libc)Access Modes.
* O_WRONLY: (libc)Access Modes.
* PARENB: (libc)Control Modes.
* PARMRK: (libc)Input Modes.
* PARODD: (libc)Control Modes.
* PATH_MAX: (libc)Limits for Files.
* PA_FLAG_MASK: (libc)Parsing a Template String.
* PENDIN: (libc)Local Modes.
* PF_FILE: (libc)Local Namespace Details.
* PF_INET6: (libc)Internet Namespace.
* PF_INET: (libc)Internet Namespace.
* PF_LOCAL: (libc)Local Namespace Details.
* PF_UNIX: (libc)Local Namespace Details.
* PIPE_BUF: (libc)Limits for Files.
* P_tmpdir: (libc)Temporary Files.
* RAND_MAX: (libc)ISO Random.
* RE_DUP_MAX: (libc)General Limits.
* RLIM_INFINITY: (libc)Limits on Resources.
* R_OK: (libc)Testing File Access.
* SA_NOCLDSTOP: (libc)Flags for Sigaction.
* SA_ONSTACK: (libc)Flags for Sigaction.
* SA_RESTART: (libc)Flags for Sigaction.
* SEEK_CUR: (libc)File Positioning.
* SEEK_END: (libc)File Positioning.
* SEEK_SET: (libc)File Positioning.
* SIGABRT: (libc)Program Error Signals.
* SIGALRM: (libc)Alarm Signals.
* SIGBUS: (libc)Program Error Signals.
* SIGCHLD: (libc)Job Control Signals.
* SIGCLD: (libc)Job Control Signals.
* SIGCONT: (libc)Job Control Signals.
* SIGEMT: (libc)Program Error Signals.
* SIGFPE: (libc)Program Error Signals.
* SIGHUP: (libc)Termination Signals.
* SIGILL: (libc)Program Error Signals.
* SIGINFO: (libc)Miscellaneous Signals.
* SIGINT: (libc)Termination Signals.
* SIGIO: (libc)Asynchronous I/O Signals.
* SIGIOT: (libc)Program Error Signals.
* SIGKILL: (libc)Termination Signals.
* SIGLOST: (libc)Operation Error Signals.
* SIGPIPE: (libc)Operation Error Signals.
* SIGPOLL: (libc)Asynchronous I/O Signals.
* SIGPROF: (libc)Alarm Signals.
* SIGQUIT: (libc)Termination Signals.
* SIGSEGV: (libc)Program Error Signals.
* SIGSTOP: (libc)Job Control Signals.
* SIGSYS: (libc)Program Error Signals.
* SIGTERM: (libc)Termination Signals.
* SIGTRAP: (libc)Program Error Signals.
* SIGTSTP: (libc)Job Control Signals.
* SIGTTIN: (libc)Job Control Signals.
* SIGTTOU: (libc)Job Control Signals.
* SIGURG: (libc)Asynchronous I/O Signals.
* SIGUSR1: (libc)Miscellaneous Signals.
* SIGUSR2: (libc)Miscellaneous Signals.
* SIGVTALRM: (libc)Alarm Signals.
* SIGWINCH: (libc)Miscellaneous Signals.
* SIGXCPU: (libc)Operation Error Signals.
* SIGXFSZ: (libc)Operation Error Signals.
* SIG_ERR: (libc)Basic Signal Handling.
* SOCK_DGRAM: (libc)Communication Styles.
* SOCK_RAW: (libc)Communication Styles.
* SOCK_RDM: (libc)Communication Styles.
* SOCK_SEQPACKET: (libc)Communication Styles.
* SOCK_STREAM: (libc)Communication Styles.
* SOL_SOCKET: (libc)Socket-Level Options.
* SSIZE_MAX: (libc)General Limits.
* STREAM_MAX: (libc)General Limits.
* SUN_LEN: (libc)Local Namespace Details.
* SV_INTERRUPT: (libc)BSD Handler.
* SV_ONSTACK: (libc)BSD Handler.
* SV_RESETHAND: (libc)BSD Handler.
* S_IFMT: (libc)Testing File Type.
* S_ISBLK: (libc)Testing File Type.
* S_ISCHR: (libc)Testing File Type.
* S_ISDIR: (libc)Testing File Type.
* S_ISFIFO: (libc)Testing File Type.
* S_ISLNK: (libc)Testing File Type.
* S_ISREG: (libc)Testing File Type.
* S_ISSOCK: (libc)Testing File Type.
* S_TYPEISMQ: (libc)Testing File Type.
* S_TYPEISSEM: (libc)Testing File Type.
* S_TYPEISSHM: (libc)Testing File Type.
* TMP_MAX: (libc)Temporary Files.
* TOSTOP: (libc)Local Modes.
* TZNAME_MAX: (libc)General Limits.
* VDISCARD: (libc)Other Special.
* VDSUSP: (libc)Signal Characters.
* VEOF: (libc)Editing Characters.
* VEOL2: (libc)Editing Characters.
* VEOL: (libc)Editing Characters.
* VERASE: (libc)Editing Characters.
* VINTR: (libc)Signal Characters.
* VKILL: (libc)Editing Characters.
* VLNEXT: (libc)Other Special.
* VMIN: (libc)Noncanonical Input.
* VQUIT: (libc)Signal Characters.
* VREPRINT: (libc)Editing Characters.
* VSTART: (libc)Start/Stop Characters.
* VSTATUS: (libc)Other Special.
* VSTOP: (libc)Start/Stop Characters.
* VSUSP: (libc)Signal Characters.
* VTIME: (libc)Noncanonical Input.
* VWERASE: (libc)Editing Characters.
* WCHAR_MAX: (libc)Extended Char Intro.
* WCHAR_MIN: (libc)Extended Char Intro.
* WCOREDUMP: (libc)Process Completion Status.
* WEOF: (libc)EOF and Errors.
* WEOF: (libc)Extended Char Intro.
* WEXITSTATUS: (libc)Process Completion Status.
* WIFEXITED: (libc)Process Completion Status.
* WIFSIGNALED: (libc)Process Completion Status.
* WIFSTOPPED: (libc)Process Completion Status.
* WSTOPSIG: (libc)Process Completion Status.
* WTERMSIG: (libc)Process Completion Status.
* W_OK: (libc)Testing File Access.
* X_OK: (libc)Testing File Access.
* _Complex_I: (libc)Complex Numbers.
* _Exit: (libc)Termination Internals.
* _IOFBF: (libc)Controlling Buffering.
* _IOLBF: (libc)Controlling Buffering.
* _IONBF: (libc)Controlling Buffering.
* _Imaginary_I: (libc)Complex Numbers.
* _PATH_UTMP: (libc)Manipulating the Database.
* _PATH_WTMP: (libc)Manipulating the Database.
* _POSIX2_C_DEV: (libc)System Options.
* _POSIX2_C_VERSION: (libc)Version Supported.
* _POSIX2_FORT_DEV: (libc)System Options.
* _POSIX2_FORT_RUN: (libc)System Options.
* _POSIX2_LOCALEDEF: (libc)System Options.
* _POSIX2_SW_DEV: (libc)System Options.
* _POSIX_CHOWN_RESTRICTED: (libc)Options for Files.
* _POSIX_JOB_CONTROL: (libc)System Options.
* _POSIX_NO_TRUNC: (libc)Options for Files.
* _POSIX_SAVED_IDS: (libc)System Options.
* _POSIX_VDISABLE: (libc)Options for Files.
* _POSIX_VERSION: (libc)Version Supported.
* __fbufsize: (libc)Controlling Buffering.
* __flbf: (libc)Controlling Buffering.
* __fpending: (libc)Controlling Buffering.
* __fpurge: (libc)Flushing Buffers.
* __freadable: (libc)Opening Streams.
* __freading: (libc)Opening Streams.
* __fsetlocking: (libc)Streams and Threads.
* __fwritable: (libc)Opening Streams.
* __fwriting: (libc)Opening Streams.
* __gconv_end_fct: (libc)glibc iconv Implementation.
* __gconv_fct: (libc)glibc iconv Implementation.
* __gconv_init_fct: (libc)glibc iconv Implementation.
* __ppc_get_timebase: (libc)PowerPC.
* __ppc_get_timebase_freq: (libc)PowerPC.
* __ppc_mdoio: (libc)PowerPC.
* __ppc_mdoom: (libc)PowerPC.
* __ppc_set_ppr_low: (libc)PowerPC.
* __ppc_set_ppr_med: (libc)PowerPC.
* __ppc_set_ppr_med_low: (libc)PowerPC.
* __ppc_yield: (libc)PowerPC.
* __va_copy: (libc)Argument Macros.
* _exit: (libc)Termination Internals.
* _flushlbf: (libc)Flushing Buffers.
* _tolower: (libc)Case Conversion.
* _toupper: (libc)Case Conversion.
* a64l: (libc)Encode Binary Data.
* abort: (libc)Aborting a Program.
* abs: (libc)Absolute Value.
* accept: (libc)Accepting Connections.
* access: (libc)Testing File Access.
* acos: (libc)Inverse Trig Functions.
* acosf: (libc)Inverse Trig Functions.
* acosh: (libc)Hyperbolic Functions.
* acoshf: (libc)Hyperbolic Functions.
* acoshl: (libc)Hyperbolic Functions.
* acosl: (libc)Inverse Trig Functions.
* addmntent: (libc)mtab.
* addseverity: (libc)Adding Severity Classes.
* adjtime: (libc)High-Resolution Calendar.
* adjtimex: (libc)High-Resolution Calendar.
* aio_cancel64: (libc)Cancel AIO Operations.
* aio_cancel: (libc)Cancel AIO Operations.
* aio_error64: (libc)Status of AIO Operations.
* aio_error: (libc)Status of AIO Operations.
* aio_fsync64: (libc)Synchronizing AIO Operations.
* aio_fsync: (libc)Synchronizing AIO Operations.
* aio_init: (libc)Configuration of AIO.
* aio_read64: (libc)Asynchronous Reads/Writes.
* aio_read: (libc)Asynchronous Reads/Writes.
* aio_return64: (libc)Status of AIO Operations.
* aio_return: (libc)Status of AIO Operations.
* aio_suspend64: (libc)Synchronizing AIO Operations.
* aio_suspend: (libc)Synchronizing AIO Operations.
* aio_write64: (libc)Asynchronous Reads/Writes.
* aio_write: (libc)Asynchronous Reads/Writes.
* alarm: (libc)Setting an Alarm.
* aligned_alloc: (libc)Aligned Memory Blocks.
* alloca: (libc)Variable Size Automatic.
* alphasort64: (libc)Scanning Directory Content.
* alphasort: (libc)Scanning Directory Content.
* argp_error: (libc)Argp Helper Functions.
* argp_failure: (libc)Argp Helper Functions.
* argp_help: (libc)Argp Help.
* argp_parse: (libc)Argp.
* argp_state_help: (libc)Argp Helper Functions.
* argp_usage: (libc)Argp Helper Functions.
* argz_add: (libc)Argz Functions.
* argz_add_sep: (libc)Argz Functions.
* argz_append: (libc)Argz Functions.
* argz_count: (libc)Argz Functions.
* argz_create: (libc)Argz Functions.
* argz_create_sep: (libc)Argz Functions.
* argz_delete: (libc)Argz Functions.
* argz_extract: (libc)Argz Functions.
* argz_insert: (libc)Argz Functions.
* argz_next: (libc)Argz Functions.
* argz_replace: (libc)Argz Functions.
* argz_stringify: (libc)Argz Functions.
* asctime: (libc)Formatting Calendar Time.
* asctime_r: (libc)Formatting Calendar Time.
* asin: (libc)Inverse Trig Functions.
* asinf: (libc)Inverse Trig Functions.
* asinh: (libc)Hyperbolic Functions.
* asinhf: (libc)Hyperbolic Functions.
* asinhl: (libc)Hyperbolic Functions.
* asinl: (libc)Inverse Trig Functions.
* asprintf: (libc)Dynamic Output.
* assert: (libc)Consistency Checking.
* assert_perror: (libc)Consistency Checking.
* atan2: (libc)Inverse Trig Functions.
* atan2f: (libc)Inverse Trig Functions.
* atan2l: (libc)Inverse Trig Functions.
* atan: (libc)Inverse Trig Functions.
* atanf: (libc)Inverse Trig Functions.
* atanh: (libc)Hyperbolic Functions.
* atanhf: (libc)Hyperbolic Functions.
* atanhl: (libc)Hyperbolic Functions.
* atanl: (libc)Inverse Trig Functions.
* atexit: (libc)Cleanups on Exit.
* atof: (libc)Parsing of Floats.
* atoi: (libc)Parsing of Integers.
* atol: (libc)Parsing of Integers.
* atoll: (libc)Parsing of Integers.
* backtrace: (libc)Backtraces.
* backtrace_symbols: (libc)Backtraces.
* backtrace_symbols_fd: (libc)Backtraces.
* basename: (libc)Finding Tokens in a String.
* basename: (libc)Finding Tokens in a String.
* bcmp: (libc)String/Array Comparison.
* bcopy: (libc)Copying and Concatenation.
* bind: (libc)Setting Address.
* bind_textdomain_codeset: (libc)Charset conversion in gettext.
* bindtextdomain: (libc)Locating gettext catalog.
* brk: (libc)Resizing the Data Segment.
* bsearch: (libc)Array Search Function.
* btowc: (libc)Converting a Character.
* bzero: (libc)Copying and Concatenation.
* cabs: (libc)Absolute Value.
* cabsf: (libc)Absolute Value.
* cabsl: (libc)Absolute Value.
* cacos: (libc)Inverse Trig Functions.
* cacosf: (libc)Inverse Trig Functions.
* cacosh: (libc)Hyperbolic Functions.
* cacoshf: (libc)Hyperbolic Functions.
* cacoshl: (libc)Hyperbolic Functions.
* cacosl: (libc)Inverse Trig Functions.
* calloc: (libc)Allocating Cleared Space.
* canonicalize_file_name: (libc)Symbolic Links.
* carg: (libc)Operations on Complex.
* cargf: (libc)Operations on Complex.
* cargl: (libc)Operations on Complex.
* casin: (libc)Inverse Trig Functions.
* casinf: (libc)Inverse Trig Functions.
* casinh: (libc)Hyperbolic Functions.
* casinhf: (libc)Hyperbolic Functions.
* casinhl: (libc)Hyperbolic Functions.
* casinl: (libc)Inverse Trig Functions.
* catan: (libc)Inverse Trig Functions.
* catanf: (libc)Inverse Trig Functions.
* catanh: (libc)Hyperbolic Functions.
* catanhf: (libc)Hyperbolic Functions.
* catanhl: (libc)Hyperbolic Functions.
* catanl: (libc)Inverse Trig Functions.
* catclose: (libc)The catgets Functions.
* catgets: (libc)The catgets Functions.
* catopen: (libc)The catgets Functions.
* cbc_crypt: (libc)DES Encryption.
* cbrt: (libc)Exponents and Logarithms.
* cbrtf: (libc)Exponents and Logarithms.
* cbrtl: (libc)Exponents and Logarithms.
* ccos: (libc)Trig Functions.
* ccosf: (libc)Trig Functions.
* ccosh: (libc)Hyperbolic Functions.
* ccoshf: (libc)Hyperbolic Functions.
* ccoshl: (libc)Hyperbolic Functions.
* ccosl: (libc)Trig Functions.
* ceil: (libc)Rounding Functions.
* ceilf: (libc)Rounding Functions.
* ceill: (libc)Rounding Functions.
* cexp: (libc)Exponents and Logarithms.
* cexpf: (libc)Exponents and Logarithms.
* cexpl: (libc)Exponents and Logarithms.
* cfgetispeed: (libc)Line Speed.
* cfgetospeed: (libc)Line Speed.
* cfmakeraw: (libc)Noncanonical Input.
* cfree: (libc)Freeing after Malloc.
* cfsetispeed: (libc)Line Speed.
* cfsetospeed: (libc)Line Speed.
* cfsetspeed: (libc)Line Speed.
* chdir: (libc)Working Directory.
* chmod: (libc)Setting Permissions.
* chown: (libc)File Owner.
* cimag: (libc)Operations on Complex.
* cimagf: (libc)Operations on Complex.
* cimagl: (libc)Operations on Complex.
* clearenv: (libc)Environment Access.
* clearerr: (libc)Error Recovery.
* clearerr_unlocked: (libc)Error Recovery.
* clock: (libc)CPU Time.
* clog10: (libc)Exponents and Logarithms.
* clog10f: (libc)Exponents and Logarithms.
* clog10l: (libc)Exponents and Logarithms.
* clog: (libc)Exponents and Logarithms.
* clogf: (libc)Exponents and Logarithms.
* clogl: (libc)Exponents and Logarithms.
* close: (libc)Opening and Closing Files.
* closedir: (libc)Reading/Closing Directory.
* closelog: (libc)closelog.
* confstr: (libc)String Parameters.
* conj: (libc)Operations on Complex.
* conjf: (libc)Operations on Complex.
* conjl: (libc)Operations on Complex.
* connect: (libc)Connecting.
* copysign: (libc)FP Bit Twiddling.
* copysignf: (libc)FP Bit Twiddling.
* copysignl: (libc)FP Bit Twiddling.
* cos: (libc)Trig Functions.
* cosf: (libc)Trig Functions.
* cosh: (libc)Hyperbolic Functions.
* coshf: (libc)Hyperbolic Functions.
* coshl: (libc)Hyperbolic Functions.
* cosl: (libc)Trig Functions.
* cpow: (libc)Exponents and Logarithms.
* cpowf: (libc)Exponents and Logarithms.
* cpowl: (libc)Exponents and Logarithms.
* cproj: (libc)Operations on Complex.
* cprojf: (libc)Operations on Complex.
* cprojl: (libc)Operations on Complex.
* creal: (libc)Operations on Complex.
* crealf: (libc)Operations on Complex.
* creall: (libc)Operations on Complex.
* creat64: (libc)Opening and Closing Files.
* creat: (libc)Opening and Closing Files.
* crypt: (libc)crypt.
* crypt_r: (libc)crypt.
* csin: (libc)Trig Functions.
* csinf: (libc)Trig Functions.
* csinh: (libc)Hyperbolic Functions.
* csinhf: (libc)Hyperbolic Functions.
* csinhl: (libc)Hyperbolic Functions.
* csinl: (libc)Trig Functions.
* csqrt: (libc)Exponents and Logarithms.
* csqrtf: (libc)Exponents and Logarithms.
* csqrtl: (libc)Exponents and Logarithms.
* ctan: (libc)Trig Functions.
* ctanf: (libc)Trig Functions.
* ctanh: (libc)Hyperbolic Functions.
* ctanhf: (libc)Hyperbolic Functions.
* ctanhl: (libc)Hyperbolic Functions.
* ctanl: (libc)Trig Functions.
* ctermid: (libc)Identifying the Terminal.
* ctime: (libc)Formatting Calendar Time.
* ctime_r: (libc)Formatting Calendar Time.
* cuserid: (libc)Who Logged In.
* dcgettext: (libc)Translation with gettext.
* dcngettext: (libc)Advanced gettext functions.
* des_setparity: (libc)DES Encryption.
* dgettext: (libc)Translation with gettext.
* difftime: (libc)Elapsed Time.
* dirfd: (libc)Opening a Directory.
* dirname: (libc)Finding Tokens in a String.
* div: (libc)Integer Division.
* dngettext: (libc)Advanced gettext functions.
* drand48: (libc)SVID Random.
* drand48_r: (libc)SVID Random.
* drem: (libc)Remainder Functions.
* dremf: (libc)Remainder Functions.
* dreml: (libc)Remainder Functions.
* dup2: (libc)Duplicating Descriptors.
* dup: (libc)Duplicating Descriptors.
* ecb_crypt: (libc)DES Encryption.
* ecvt: (libc)System V Number Conversion.
* ecvt_r: (libc)System V Number Conversion.
* encrypt: (libc)DES Encryption.
* encrypt_r: (libc)DES Encryption.
* endfsent: (libc)fstab.
* endgrent: (libc)Scanning All Groups.
* endhostent: (libc)Host Names.
* endmntent: (libc)mtab.
* endnetent: (libc)Networks Database.
* endnetgrent: (libc)Lookup Netgroup.
* endprotoent: (libc)Protocols Database.
* endpwent: (libc)Scanning All Users.
* endservent: (libc)Services Database.
* endutent: (libc)Manipulating the Database.
* endutxent: (libc)XPG Functions.
* envz_add: (libc)Envz Functions.
* envz_entry: (libc)Envz Functions.
* envz_get: (libc)Envz Functions.
* envz_merge: (libc)Envz Functions.
* envz_strip: (libc)Envz Functions.
* erand48: (libc)SVID Random.
* erand48_r: (libc)SVID Random.
* erf: (libc)Special Functions.
* erfc: (libc)Special Functions.
* erfcf: (libc)Special Functions.
* erfcl: (libc)Special Functions.
* erff: (libc)Special Functions.
* erfl: (libc)Special Functions.
* err: (libc)Error Messages.
* errno: (libc)Checking for Errors.
* error: (libc)Error Messages.
* error_at_line: (libc)Error Messages.
* errx: (libc)Error Messages.
* execl: (libc)Executing a File.
* execle: (libc)Executing a File.
* execlp: (libc)Executing a File.
* execv: (libc)Executing a File.
* execve: (libc)Executing a File.
* execvp: (libc)Executing a File.
* exit: (libc)Normal Termination.
* exp10: (libc)Exponents and Logarithms.
* exp10f: (libc)Exponents and Logarithms.
* exp10l: (libc)Exponents and Logarithms.
* exp2: (libc)Exponents and Logarithms.
* exp2f: (libc)Exponents and Logarithms.
* exp2l: (libc)Exponents and Logarithms.
* exp: (libc)Exponents and Logarithms.
* expf: (libc)Exponents and Logarithms.
* expl: (libc)Exponents and Logarithms.
* expm1: (libc)Exponents and Logarithms.
* expm1f: (libc)Exponents and Logarithms.
* expm1l: (libc)Exponents and Logarithms.
* fabs: (libc)Absolute Value.
* fabsf: (libc)Absolute Value.
* fabsl: (libc)Absolute Value.
* fchdir: (libc)Working Directory.
* fchmod: (libc)Setting Permissions.
* fchown: (libc)File Owner.
* fclose: (libc)Closing Streams.
* fcloseall: (libc)Closing Streams.
* fcntl: (libc)Control Operations.
* fcvt: (libc)System V Number Conversion.
* fcvt_r: (libc)System V Number Conversion.
* fdatasync: (libc)Synchronizing I/O.
* fdim: (libc)Misc FP Arithmetic.
* fdimf: (libc)Misc FP Arithmetic.
* fdiml: (libc)Misc FP Arithmetic.
* fdopen: (libc)Descriptors and Streams.
* fdopendir: (libc)Opening a Directory.
* feclearexcept: (libc)Status bit operations.
* fedisableexcept: (libc)Control Functions.
* feenableexcept: (libc)Control Functions.
* fegetenv: (libc)Control Functions.
* fegetexcept: (libc)Control Functions.
* fegetexceptflag: (libc)Status bit operations.
* fegetround: (libc)Rounding.
* feholdexcept: (libc)Control Functions.
* feof: (libc)EOF and Errors.
* feof_unlocked: (libc)EOF and Errors.
* feraiseexcept: (libc)Status bit operations.
* ferror: (libc)EOF and Errors.
* ferror_unlocked: (libc)EOF and Errors.
* fesetenv: (libc)Control Functions.
* fesetexceptflag: (libc)Status bit operations.
* fesetround: (libc)Rounding.
* fetestexcept: (libc)Status bit operations.
* feupdateenv: (libc)Control Functions.
* fflush: (libc)Flushing Buffers.
* fflush_unlocked: (libc)Flushing Buffers.
* fgetc: (libc)Character Input.
* fgetc_unlocked: (libc)Character Input.
* fgetgrent: (libc)Scanning All Groups.
* fgetgrent_r: (libc)Scanning All Groups.
* fgetpos64: (libc)Portable Positioning.
* fgetpos: (libc)Portable Positioning.
* fgetpwent: (libc)Scanning All Users.
* fgetpwent_r: (libc)Scanning All Users.
* fgets: (libc)Line Input.
* fgets_unlocked: (libc)Line Input.
* fgetwc: (libc)Character Input.
* fgetwc_unlocked: (libc)Character Input.
* fgetws: (libc)Line Input.
* fgetws_unlocked: (libc)Line Input.
* fileno: (libc)Descriptors and Streams.
* fileno_unlocked: (libc)Descriptors and Streams.
* finite: (libc)Floating Point Classes.
* finitef: (libc)Floating Point Classes.
* finitel: (libc)Floating Point Classes.
* flockfile: (libc)Streams and Threads.
* floor: (libc)Rounding Functions.
* floorf: (libc)Rounding Functions.
* floorl: (libc)Rounding Functions.
* fma: (libc)Misc FP Arithmetic.
* fmaf: (libc)Misc FP Arithmetic.
* fmal: (libc)Misc FP Arithmetic.
* fmax: (libc)Misc FP Arithmetic.
* fmaxf: (libc)Misc FP Arithmetic.
* fmaxl: (libc)Misc FP Arithmetic.
* fmemopen: (libc)String Streams.
* fmin: (libc)Misc FP Arithmetic.
* fminf: (libc)Misc FP Arithmetic.
* fminl: (libc)Misc FP Arithmetic.
* fmod: (libc)Remainder Functions.
* fmodf: (libc)Remainder Functions.
* fmodl: (libc)Remainder Functions.
* fmtmsg: (libc)Printing Formatted Messages.
* fnmatch: (libc)Wildcard Matching.
* fopen64: (libc)Opening Streams.
* fopen: (libc)Opening Streams.
* fopencookie: (libc)Streams and Cookies.
* fork: (libc)Creating a Process.
* forkpty: (libc)Pseudo-Terminal Pairs.
* fpathconf: (libc)Pathconf.
* fpclassify: (libc)Floating Point Classes.
* fprintf: (libc)Formatted Output Functions.
* fputc: (libc)Simple Output.
* fputc_unlocked: (libc)Simple Output.
* fputs: (libc)Simple Output.
* fputs_unlocked: (libc)Simple Output.
* fputwc: (libc)Simple Output.
* fputwc_unlocked: (libc)Simple Output.
* fputws: (libc)Simple Output.
* fputws_unlocked: (libc)Simple Output.
* fread: (libc)Block Input/Output.
* fread_unlocked: (libc)Block Input/Output.
* free: (libc)Freeing after Malloc.
* freopen64: (libc)Opening Streams.
* freopen: (libc)Opening Streams.
* frexp: (libc)Normalization Functions.
* frexpf: (libc)Normalization Functions.
* frexpl: (libc)Normalization Functions.
* fscanf: (libc)Formatted Input Functions.
* fseek: (libc)File Positioning.
* fseeko64: (libc)File Positioning.
* fseeko: (libc)File Positioning.
* fsetpos64: (libc)Portable Positioning.
* fsetpos: (libc)Portable Positioning.
* fstat64: (libc)Reading Attributes.
* fstat: (libc)Reading Attributes.
* fsync: (libc)Synchronizing I/O.
* ftell: (libc)File Positioning.
* ftello64: (libc)File Positioning.
* ftello: (libc)File Positioning.
* ftruncate64: (libc)File Size.
* ftruncate: (libc)File Size.
* ftrylockfile: (libc)Streams and Threads.
* ftw64: (libc)Working with Directory Trees.
* ftw: (libc)Working with Directory Trees.
* funlockfile: (libc)Streams and Threads.
* futimes: (libc)File Times.
* fwide: (libc)Streams and I18N.
* fwprintf: (libc)Formatted Output Functions.
* fwrite: (libc)Block Input/Output.
* fwrite_unlocked: (libc)Block Input/Output.
* fwscanf: (libc)Formatted Input Functions.
* gamma: (libc)Special Functions.
* gammaf: (libc)Special Functions.
* gammal: (libc)Special Functions.
* gcvt: (libc)System V Number Conversion.
* get_avphys_pages: (libc)Query Memory Parameters.
* get_current_dir_name: (libc)Working Directory.
* get_nprocs: (libc)Processor Resources.
* get_nprocs_conf: (libc)Processor Resources.
* get_phys_pages: (libc)Query Memory Parameters.
* getauxval: (libc)Auxiliary Vector.
* getc: (libc)Character Input.
* getc_unlocked: (libc)Character Input.
* getchar: (libc)Character Input.
* getchar_unlocked: (libc)Character Input.
* getcontext: (libc)System V contexts.
* getcwd: (libc)Working Directory.
* getdate: (libc)General Time String Parsing.
* getdate_r: (libc)General Time String Parsing.
* getdelim: (libc)Line Input.
* getdomainnname: (libc)Host Identification.
* getegid: (libc)Reading Persona.
* getenv: (libc)Environment Access.
* geteuid: (libc)Reading Persona.
* getfsent: (libc)fstab.
* getfsfile: (libc)fstab.
* getfsspec: (libc)fstab.
* getgid: (libc)Reading Persona.
* getgrent: (libc)Scanning All Groups.
* getgrent_r: (libc)Scanning All Groups.
* getgrgid: (libc)Lookup Group.
* getgrgid_r: (libc)Lookup Group.
* getgrnam: (libc)Lookup Group.
* getgrnam_r: (libc)Lookup Group.
* getgrouplist: (libc)Setting Groups.
* getgroups: (libc)Reading Persona.
* gethostbyaddr: (libc)Host Names.
* gethostbyaddr_r: (libc)Host Names.
* gethostbyname2: (libc)Host Names.
* gethostbyname2_r: (libc)Host Names.
* gethostbyname: (libc)Host Names.
* gethostbyname_r: (libc)Host Names.
* gethostent: (libc)Host Names.
* gethostid: (libc)Host Identification.
* gethostname: (libc)Host Identification.
* getitimer: (libc)Setting an Alarm.
* getline: (libc)Line Input.
* getloadavg: (libc)Processor Resources.
* getlogin: (libc)Who Logged In.
* getmntent: (libc)mtab.
* getmntent_r: (libc)mtab.
* getnetbyaddr: (libc)Networks Database.
* getnetbyname: (libc)Networks Database.
* getnetent: (libc)Networks Database.
* getnetgrent: (libc)Lookup Netgroup.
* getnetgrent_r: (libc)Lookup Netgroup.
* getopt: (libc)Using Getopt.
* getopt_long: (libc)Getopt Long Options.
* getopt_long_only: (libc)Getopt Long Options.
* getpagesize: (libc)Query Memory Parameters.
* getpass: (libc)getpass.
* getpeername: (libc)Who is Connected.
* getpgid: (libc)Process Group Functions.
* getpgrp: (libc)Process Group Functions.
* getpid: (libc)Process Identification.
* getppid: (libc)Process Identification.
* getpriority: (libc)Traditional Scheduling Functions.
* getprotobyname: (libc)Protocols Database.
* getprotobynumber: (libc)Protocols Database.
* getprotoent: (libc)Protocols Database.
* getpt: (libc)Allocation.
* getpwent: (libc)Scanning All Users.
* getpwent_r: (libc)Scanning All Users.
* getpwnam: (libc)Lookup User.
* getpwnam_r: (libc)Lookup User.
* getpwuid: (libc)Lookup User.
* getpwuid_r: (libc)Lookup User.
* getrlimit64: (libc)Limits on Resources.
* getrlimit: (libc)Limits on Resources.
* getrusage: (libc)Resource Usage.
* gets: (libc)Line Input.
* getservbyname: (libc)Services Database.
* getservbyport: (libc)Services Database.
* getservent: (libc)Services Database.
* getsid: (libc)Process Group Functions.
* getsockname: (libc)Reading Address.
* getsockopt: (libc)Socket Option Functions.
* getsubopt: (libc)Suboptions.
* gettext: (libc)Translation with gettext.
* gettimeofday: (libc)High-Resolution Calendar.
* getuid: (libc)Reading Persona.
* getumask: (libc)Setting Permissions.
* getutent: (libc)Manipulating the Database.
* getutent_r: (libc)Manipulating the Database.
* getutid: (libc)Manipulating the Database.
* getutid_r: (libc)Manipulating the Database.
* getutline: (libc)Manipulating the Database.
* getutline_r: (libc)Manipulating the Database.
* getutmp: (libc)XPG Functions.
* getutmpx: (libc)XPG Functions.
* getutxent: (libc)XPG Functions.
* getutxid: (libc)XPG Functions.
* getutxline: (libc)XPG Functions.
* getw: (libc)Character Input.
* getwc: (libc)Character Input.
* getwc_unlocked: (libc)Character Input.
* getwchar: (libc)Character Input.
* getwchar_unlocked: (libc)Character Input.
* getwd: (libc)Working Directory.
* glob64: (libc)Calling Glob.
* glob: (libc)Calling Glob.
* globfree64: (libc)More Flags for Globbing.
* globfree: (libc)More Flags for Globbing.
* gmtime: (libc)Broken-down Time.
* gmtime_r: (libc)Broken-down Time.
* grantpt: (libc)Allocation.
* gsignal: (libc)Signaling Yourself.
* gtty: (libc)BSD Terminal Modes.
* hasmntopt: (libc)mtab.
* hcreate: (libc)Hash Search Function.
* hcreate_r: (libc)Hash Search Function.
* hdestroy: (libc)Hash Search Function.
* hdestroy_r: (libc)Hash Search Function.
* hsearch: (libc)Hash Search Function.
* hsearch_r: (libc)Hash Search Function.
* htonl: (libc)Byte Order.
* htons: (libc)Byte Order.
* hypot: (libc)Exponents and Logarithms.
* hypotf: (libc)Exponents and Logarithms.
* hypotl: (libc)Exponents and Logarithms.
* iconv: (libc)Generic Conversion Interface.
* iconv_close: (libc)Generic Conversion Interface.
* iconv_open: (libc)Generic Conversion Interface.
* if_freenameindex: (libc)Interface Naming.
* if_indextoname: (libc)Interface Naming.
* if_nameindex: (libc)Interface Naming.
* if_nametoindex: (libc)Interface Naming.
* ilogb: (libc)Exponents and Logarithms.
* ilogbf: (libc)Exponents and Logarithms.
* ilogbl: (libc)Exponents and Logarithms.
* imaxabs: (libc)Absolute Value.
* imaxdiv: (libc)Integer Division.
* in6addr_any: (libc)Host Address Data Type.
* in6addr_loopback: (libc)Host Address Data Type.
* index: (libc)Search Functions.
* inet_addr: (libc)Host Address Functions.
* inet_aton: (libc)Host Address Functions.
* inet_lnaof: (libc)Host Address Functions.
* inet_makeaddr: (libc)Host Address Functions.
* inet_netof: (libc)Host Address Functions.
* inet_network: (libc)Host Address Functions.
* inet_ntoa: (libc)Host Address Functions.
* inet_ntop: (libc)Host Address Functions.
* inet_pton: (libc)Host Address Functions.
* initgroups: (libc)Setting Groups.
* initstate: (libc)BSD Random.
* initstate_r: (libc)BSD Random.
* innetgr: (libc)Netgroup Membership.
* ioctl: (libc)IOCTLs.
* isalnum: (libc)Classification of Characters.
* isalpha: (libc)Classification of Characters.
* isascii: (libc)Classification of Characters.
* isatty: (libc)Is It a Terminal.
* isblank: (libc)Classification of Characters.
* iscntrl: (libc)Classification of Characters.
* isdigit: (libc)Classification of Characters.
* isfinite: (libc)Floating Point Classes.
* isgraph: (libc)Classification of Characters.
* isgreater: (libc)FP Comparison Functions.
* isgreaterequal: (libc)FP Comparison Functions.
* isinf: (libc)Floating Point Classes.
* isinff: (libc)Floating Point Classes.
* isinfl: (libc)Floating Point Classes.
* isless: (libc)FP Comparison Functions.
* islessequal: (libc)FP Comparison Functions.
* islessgreater: (libc)FP Comparison Functions.
* islower: (libc)Classification of Characters.
* isnan: (libc)Floating Point Classes.
* isnan: (libc)Floating Point Classes.
* isnanf: (libc)Floating Point Classes.
* isnanl: (libc)Floating Point Classes.
* isnormal: (libc)Floating Point Classes.
* isprint: (libc)Classification of Characters.
* ispunct: (libc)Classification of Characters.
* issignaling: (libc)Floating Point Classes.
* isspace: (libc)Classification of Characters.
* isunordered: (libc)FP Comparison Functions.
* isupper: (libc)Classification of Characters.
* iswalnum: (libc)Classification of Wide Characters.
* iswalpha: (libc)Classification of Wide Characters.
* iswblank: (libc)Classification of Wide Characters.
* iswcntrl: (libc)Classification of Wide Characters.
* iswctype: (libc)Classification of Wide Characters.
* iswdigit: (libc)Classification of Wide Characters.
* iswgraph: (libc)Classification of Wide Characters.
* iswlower: (libc)Classification of Wide Characters.
* iswprint: (libc)Classification of Wide Characters.
* iswpunct: (libc)Classification of Wide Characters.
* iswspace: (libc)Classification of Wide Characters.
* iswupper: (libc)Classification of Wide Characters.
* iswxdigit: (libc)Classification of Wide Characters.
* isxdigit: (libc)Classification of Characters.
* j0: (libc)Special Functions.
* j0f: (libc)Special Functions.
* j0l: (libc)Special Functions.
* j1: (libc)Special Functions.
* j1f: (libc)Special Functions.
* j1l: (libc)Special Functions.
* jn: (libc)Special Functions.
* jnf: (libc)Special Functions.
* jnl: (libc)Special Functions.
* jrand48: (libc)SVID Random.
* jrand48_r: (libc)SVID Random.
* kill: (libc)Signaling Another Process.
* killpg: (libc)Signaling Another Process.
* l64a: (libc)Encode Binary Data.
* labs: (libc)Absolute Value.
* lcong48: (libc)SVID Random.
* lcong48_r: (libc)SVID Random.
* ldexp: (libc)Normalization Functions.
* ldexpf: (libc)Normalization Functions.
* ldexpl: (libc)Normalization Functions.
* ldiv: (libc)Integer Division.
* lfind: (libc)Array Search Function.
* lgamma: (libc)Special Functions.
* lgamma_r: (libc)Special Functions.
* lgammaf: (libc)Special Functions.
* lgammaf_r: (libc)Special Functions.
* lgammal: (libc)Special Functions.
* lgammal_r: (libc)Special Functions.
* link: (libc)Hard Links.
* lio_listio64: (libc)Asynchronous Reads/Writes.
* lio_listio: (libc)Asynchronous Reads/Writes.
* listen: (libc)Listening.
* llabs: (libc)Absolute Value.
* lldiv: (libc)Integer Division.
* llrint: (libc)Rounding Functions.
* llrintf: (libc)Rounding Functions.
* llrintl: (libc)Rounding Functions.
* llround: (libc)Rounding Functions.
* llroundf: (libc)Rounding Functions.
* llroundl: (libc)Rounding Functions.
* localeconv: (libc)The Lame Way to Locale Data.
* localtime: (libc)Broken-down Time.
* localtime_r: (libc)Broken-down Time.
* log10: (libc)Exponents and Logarithms.
* log10f: (libc)Exponents and Logarithms.
* log10l: (libc)Exponents and Logarithms.
* log1p: (libc)Exponents and Logarithms.
* log1pf: (libc)Exponents and Logarithms.
* log1pl: (libc)Exponents and Logarithms.
* log2: (libc)Exponents and Logarithms.
* log2f: (libc)Exponents and Logarithms.
* log2l: (libc)Exponents and Logarithms.
* log: (libc)Exponents and Logarithms.
* logb: (libc)Exponents and Logarithms.
* logbf: (libc)Exponents and Logarithms.
* logbl: (libc)Exponents and Logarithms.
* logf: (libc)Exponents and Logarithms.
* login: (libc)Logging In and Out.
* login_tty: (libc)Logging In and Out.
* logl: (libc)Exponents and Logarithms.
* logout: (libc)Logging In and Out.
* logwtmp: (libc)Logging In and Out.
* longjmp: (libc)Non-Local Details.
* lrand48: (libc)SVID Random.
* lrand48_r: (libc)SVID Random.
* lrint: (libc)Rounding Functions.
* lrintf: (libc)Rounding Functions.
* lrintl: (libc)Rounding Functions.
* lround: (libc)Rounding Functions.
* lroundf: (libc)Rounding Functions.
* lroundl: (libc)Rounding Functions.
* lsearch: (libc)Array Search Function.
* lseek64: (libc)File Position Primitive.
* lseek: (libc)File Position Primitive.
* lstat64: (libc)Reading Attributes.
* lstat: (libc)Reading Attributes.
* lutimes: (libc)File Times.
* madvise: (libc)Memory-mapped I/O.
* makecontext: (libc)System V contexts.
* mallinfo: (libc)Statistics of Malloc.
* malloc: (libc)Basic Allocation.
* mallopt: (libc)Malloc Tunable Parameters.
* mblen: (libc)Non-reentrant Character Conversion.
* mbrlen: (libc)Converting a Character.
* mbrtowc: (libc)Converting a Character.
* mbsinit: (libc)Keeping the state.
* mbsnrtowcs: (libc)Converting Strings.
* mbsrtowcs: (libc)Converting Strings.
* mbstowcs: (libc)Non-reentrant String Conversion.
* mbtowc: (libc)Non-reentrant Character Conversion.
* mcheck: (libc)Heap Consistency Checking.
* memalign: (libc)Aligned Memory Blocks.
* memccpy: (libc)Copying and Concatenation.
* memchr: (libc)Search Functions.
* memcmp: (libc)String/Array Comparison.
* memcpy: (libc)Copying and Concatenation.
* memfrob: (libc)Trivial Encryption.
* memmem: (libc)Search Functions.
* memmove: (libc)Copying and Concatenation.
* mempcpy: (libc)Copying and Concatenation.
* memrchr: (libc)Search Functions.
* memset: (libc)Copying and Concatenation.
* mkdir: (libc)Creating Directories.
* mkdtemp: (libc)Temporary Files.
* mkfifo: (libc)FIFO Special Files.
* mknod: (libc)Making Special Files.
* mkstemp: (libc)Temporary Files.
* mktemp: (libc)Temporary Files.
* mktime: (libc)Broken-down Time.
* mlock: (libc)Page Lock Functions.
* mlockall: (libc)Page Lock Functions.
* mmap64: (libc)Memory-mapped I/O.
* mmap: (libc)Memory-mapped I/O.
* modf: (libc)Rounding Functions.
* modff: (libc)Rounding Functions.
* modfl: (libc)Rounding Functions.
* mount: (libc)Mount-Unmount-Remount.
* mprobe: (libc)Heap Consistency Checking.
* mrand48: (libc)SVID Random.
* mrand48_r: (libc)SVID Random.
* mremap: (libc)Memory-mapped I/O.
* msync: (libc)Memory-mapped I/O.
* mtrace: (libc)Tracing malloc.
* munlock: (libc)Page Lock Functions.
* munlockall: (libc)Page Lock Functions.
* munmap: (libc)Memory-mapped I/O.
* muntrace: (libc)Tracing malloc.
* nan: (libc)FP Bit Twiddling.
* nanf: (libc)FP Bit Twiddling.
* nanl: (libc)FP Bit Twiddling.
* nanosleep: (libc)Sleeping.
* nearbyint: (libc)Rounding Functions.
* nearbyintf: (libc)Rounding Functions.
* nearbyintl: (libc)Rounding Functions.
* nextafter: (libc)FP Bit Twiddling.
* nextafterf: (libc)FP Bit Twiddling.
* nextafterl: (libc)FP Bit Twiddling.
* nexttoward: (libc)FP Bit Twiddling.
* nexttowardf: (libc)FP Bit Twiddling.
* nexttowardl: (libc)FP Bit Twiddling.
* nftw64: (libc)Working with Directory Trees.
* nftw: (libc)Working with Directory Trees.
* ngettext: (libc)Advanced gettext functions.
* nice: (libc)Traditional Scheduling Functions.
* nl_langinfo: (libc)The Elegant and Fast Way.
* nrand48: (libc)SVID Random.
* nrand48_r: (libc)SVID Random.
* ntohl: (libc)Byte Order.
* ntohs: (libc)Byte Order.
* ntp_adjtime: (libc)High Accuracy Clock.
* ntp_gettime: (libc)High Accuracy Clock.
* obstack_1grow: (libc)Growing Objects.
* obstack_1grow_fast: (libc)Extra Fast Growing.
* obstack_alignment_mask: (libc)Obstacks Data Alignment.
* obstack_alloc: (libc)Allocation in an Obstack.
* obstack_base: (libc)Status of an Obstack.
* obstack_blank: (libc)Growing Objects.
* obstack_blank_fast: (libc)Extra Fast Growing.
* obstack_chunk_size: (libc)Obstack Chunks.
* obstack_copy0: (libc)Allocation in an Obstack.
* obstack_copy: (libc)Allocation in an Obstack.
* obstack_finish: (libc)Growing Objects.
* obstack_free: (libc)Freeing Obstack Objects.
* obstack_grow0: (libc)Growing Objects.
* obstack_grow: (libc)Growing Objects.
* obstack_init: (libc)Preparing for Obstacks.
* obstack_int_grow: (libc)Growing Objects.
* obstack_int_grow_fast: (libc)Extra Fast Growing.
* obstack_next_free: (libc)Status of an Obstack.
* obstack_object_size: (libc)Growing Objects.
* obstack_object_size: (libc)Status of an Obstack.
* obstack_printf: (libc)Dynamic Output.
* obstack_ptr_grow: (libc)Growing Objects.
* obstack_ptr_grow_fast: (libc)Extra Fast Growing.
* obstack_room: (libc)Extra Fast Growing.
* obstack_vprintf: (libc)Variable Arguments Output.
* offsetof: (libc)Structure Measurement.
* on_exit: (libc)Cleanups on Exit.
* open64: (libc)Opening and Closing Files.
* open: (libc)Opening and Closing Files.
* open_memstream: (libc)String Streams.
* opendir: (libc)Opening a Directory.
* openlog: (libc)openlog.
* openpty: (libc)Pseudo-Terminal Pairs.
* parse_printf_format: (libc)Parsing a Template String.
* pathconf: (libc)Pathconf.
* pause: (libc)Using Pause.
* pclose: (libc)Pipe to a Subprocess.
* perror: (libc)Error Messages.
* pipe: (libc)Creating a Pipe.
* popen: (libc)Pipe to a Subprocess.
* posix_memalign: (libc)Aligned Memory Blocks.
* pow10: (libc)Exponents and Logarithms.
* pow10f: (libc)Exponents and Logarithms.
* pow10l: (libc)Exponents and Logarithms.
* pow: (libc)Exponents and Logarithms.
* powf: (libc)Exponents and Logarithms.
* powl: (libc)Exponents and Logarithms.
* pread64: (libc)I/O Primitives.
* pread: (libc)I/O Primitives.
* printf: (libc)Formatted Output Functions.
* printf_size: (libc)Predefined Printf Handlers.
* printf_size_info: (libc)Predefined Printf Handlers.
* psignal: (libc)Signal Messages.
* pthread_getattr_default_np: (libc)Default Thread Attributes.
* pthread_getspecific: (libc)Thread-specific Data.
* pthread_key_create: (libc)Thread-specific Data.
* pthread_key_delete: (libc)Thread-specific Data.
* pthread_setattr_default_np: (libc)Default Thread Attributes.
* pthread_setspecific: (libc)Thread-specific Data.
* ptsname: (libc)Allocation.
* ptsname_r: (libc)Allocation.
* putc: (libc)Simple Output.
* putc_unlocked: (libc)Simple Output.
* putchar: (libc)Simple Output.
* putchar_unlocked: (libc)Simple Output.
* putenv: (libc)Environment Access.
* putpwent: (libc)Writing a User Entry.
* puts: (libc)Simple Output.
* pututline: (libc)Manipulating the Database.
* pututxline: (libc)XPG Functions.
* putw: (libc)Simple Output.
* putwc: (libc)Simple Output.
* putwc_unlocked: (libc)Simple Output.
* putwchar: (libc)Simple Output.
* putwchar_unlocked: (libc)Simple Output.
* pwrite64: (libc)I/O Primitives.
* pwrite: (libc)I/O Primitives.
* qecvt: (libc)System V Number Conversion.
* qecvt_r: (libc)System V Number Conversion.
* qfcvt: (libc)System V Number Conversion.
* qfcvt_r: (libc)System V Number Conversion.
* qgcvt: (libc)System V Number Conversion.
* qsort: (libc)Array Sort Function.
* raise: (libc)Signaling Yourself.
* rand: (libc)ISO Random.
* rand_r: (libc)ISO Random.
* random: (libc)BSD Random.
* random_r: (libc)BSD Random.
* rawmemchr: (libc)Search Functions.
* read: (libc)I/O Primitives.
* readdir64: (libc)Reading/Closing Directory.
* readdir64_r: (libc)Reading/Closing Directory.
* readdir: (libc)Reading/Closing Directory.
* readdir_r: (libc)Reading/Closing Directory.
* readlink: (libc)Symbolic Links.
* readv: (libc)Scatter-Gather.
* realloc: (libc)Changing Block Size.
* realpath: (libc)Symbolic Links.
* recv: (libc)Receiving Data.
* recvfrom: (libc)Receiving Datagrams.
* recvmsg: (libc)Receiving Datagrams.
* regcomp: (libc)POSIX Regexp Compilation.
* regerror: (libc)Regexp Cleanup.
* regexec: (libc)Matching POSIX Regexps.
* regfree: (libc)Regexp Cleanup.
* register_printf_function: (libc)Registering New Conversions.
* remainder: (libc)Remainder Functions.
* remainderf: (libc)Remainder Functions.
* remainderl: (libc)Remainder Functions.
* remove: (libc)Deleting Files.
* rename: (libc)Renaming Files.
* rewind: (libc)File Positioning.
* rewinddir: (libc)Random Access Directory.
* rindex: (libc)Search Functions.
* rint: (libc)Rounding Functions.
* rintf: (libc)Rounding Functions.
* rintl: (libc)Rounding Functions.
* rmdir: (libc)Deleting Files.
* round: (libc)Rounding Functions.
* roundf: (libc)Rounding Functions.
* roundl: (libc)Rounding Functions.
* rpmatch: (libc)Yes-or-No Questions.
* sbrk: (libc)Resizing the Data Segment.
* scalb: (libc)Normalization Functions.
* scalbf: (libc)Normalization Functions.
* scalbl: (libc)Normalization Functions.
* scalbln: (libc)Normalization Functions.
* scalblnf: (libc)Normalization Functions.
* scalblnl: (libc)Normalization Functions.
* scalbn: (libc)Normalization Functions.
* scalbnf: (libc)Normalization Functions.
* scalbnl: (libc)Normalization Functions.
* scandir64: (libc)Scanning Directory Content.
* scandir: (libc)Scanning Directory Content.
* scanf: (libc)Formatted Input Functions.
* sched_get_priority_max: (libc)Basic Scheduling Functions.
* sched_get_priority_min: (libc)Basic Scheduling Functions.
* sched_getaffinity: (libc)CPU Affinity.
* sched_getparam: (libc)Basic Scheduling Functions.
* sched_getscheduler: (libc)Basic Scheduling Functions.
* sched_rr_get_interval: (libc)Basic Scheduling Functions.
* sched_setaffinity: (libc)CPU Affinity.
* sched_setparam: (libc)Basic Scheduling Functions.
* sched_setscheduler: (libc)Basic Scheduling Functions.
* sched_yield: (libc)Basic Scheduling Functions.
* secure_getenv: (libc)Environment Access.
* seed48: (libc)SVID Random.
* seed48_r: (libc)SVID Random.
* seekdir: (libc)Random Access Directory.
* select: (libc)Waiting for I/O.
* send: (libc)Sending Data.
* sendmsg: (libc)Receiving Datagrams.
* sendto: (libc)Sending Datagrams.
* setbuf: (libc)Controlling Buffering.
* setbuffer: (libc)Controlling Buffering.
* setcontext: (libc)System V contexts.
* setdomainname: (libc)Host Identification.
* setegid: (libc)Setting Groups.
* setenv: (libc)Environment Access.
* seteuid: (libc)Setting User ID.
* setfsent: (libc)fstab.
* setgid: (libc)Setting Groups.
* setgrent: (libc)Scanning All Groups.
* setgroups: (libc)Setting Groups.
* sethostent: (libc)Host Names.
* sethostid: (libc)Host Identification.
* sethostname: (libc)Host Identification.
* setitimer: (libc)Setting an Alarm.
* setjmp: (libc)Non-Local Details.
* setkey: (libc)DES Encryption.
* setkey_r: (libc)DES Encryption.
* setlinebuf: (libc)Controlling Buffering.
* setlocale: (libc)Setting the Locale.
* setlogmask: (libc)setlogmask.
* setmntent: (libc)mtab.
* setnetent: (libc)Networks Database.
* setnetgrent: (libc)Lookup Netgroup.
* setpgid: (libc)Process Group Functions.
* setpgrp: (libc)Process Group Functions.
* setpriority: (libc)Traditional Scheduling Functions.
* setprotoent: (libc)Protocols Database.
* setpwent: (libc)Scanning All Users.
* setregid: (libc)Setting Groups.
* setreuid: (libc)Setting User ID.
* setrlimit64: (libc)Limits on Resources.
* setrlimit: (libc)Limits on Resources.
* setservent: (libc)Services Database.
* setsid: (libc)Process Group Functions.
* setsockopt: (libc)Socket Option Functions.
* setstate: (libc)BSD Random.
* setstate_r: (libc)BSD Random.
* settimeofday: (libc)High-Resolution Calendar.
* setuid: (libc)Setting User ID.
* setutent: (libc)Manipulating the Database.
* setutxent: (libc)XPG Functions.
* setvbuf: (libc)Controlling Buffering.
* shm_open: (libc)Memory-mapped I/O.
* shm_unlink: (libc)Memory-mapped I/O.
* shutdown: (libc)Closing a Socket.
* sigaction: (libc)Advanced Signal Handling.
* sigaddset: (libc)Signal Sets.
* sigaltstack: (libc)Signal Stack.
* sigblock: (libc)Blocking in BSD.
* sigdelset: (libc)Signal Sets.
* sigemptyset: (libc)Signal Sets.
* sigfillset: (libc)Signal Sets.
* siginterrupt: (libc)BSD Handler.
* sigismember: (libc)Signal Sets.
* siglongjmp: (libc)Non-Local Exits and Signals.
* sigmask: (libc)Blocking in BSD.
* signal: (libc)Basic Signal Handling.
* signbit: (libc)FP Bit Twiddling.
* significand: (libc)Normalization Functions.
* significandf: (libc)Normalization Functions.
* significandl: (libc)Normalization Functions.
* sigpause: (libc)Blocking in BSD.
* sigpending: (libc)Checking for Pending Signals.
* sigprocmask: (libc)Process Signal Mask.
* sigsetjmp: (libc)Non-Local Exits and Signals.
* sigsetmask: (libc)Blocking in BSD.
* sigstack: (libc)Signal Stack.
* sigsuspend: (libc)Sigsuspend.
* sigvec: (libc)BSD Handler.
* sin: (libc)Trig Functions.
* sincos: (libc)Trig Functions.
* sincosf: (libc)Trig Functions.
* sincosl: (libc)Trig Functions.
* sinf: (libc)Trig Functions.
* sinh: (libc)Hyperbolic Functions.
* sinhf: (libc)Hyperbolic Functions.
* sinhl: (libc)Hyperbolic Functions.
* sinl: (libc)Trig Functions.
* sleep: (libc)Sleeping.
* snprintf: (libc)Formatted Output Functions.
* socket: (libc)Creating a Socket.
* socketpair: (libc)Socket Pairs.
* sprintf: (libc)Formatted Output Functions.
* sqrt: (libc)Exponents and Logarithms.
* sqrtf: (libc)Exponents and Logarithms.
* sqrtl: (libc)Exponents and Logarithms.
* srand48: (libc)SVID Random.
* srand48_r: (libc)SVID Random.
* srand: (libc)ISO Random.
* srandom: (libc)BSD Random.
* srandom_r: (libc)BSD Random.
* sscanf: (libc)Formatted Input Functions.
* ssignal: (libc)Basic Signal Handling.
* stat64: (libc)Reading Attributes.
* stat: (libc)Reading Attributes.
* stime: (libc)Simple Calendar Time.
* stpcpy: (libc)Copying and Concatenation.
* stpncpy: (libc)Copying and Concatenation.
* strcasecmp: (libc)String/Array Comparison.
* strcasestr: (libc)Search Functions.
* strcat: (libc)Copying and Concatenation.
* strchr: (libc)Search Functions.
* strchrnul: (libc)Search Functions.
* strcmp: (libc)String/Array Comparison.
* strcoll: (libc)Collation Functions.
* strcpy: (libc)Copying and Concatenation.
* strcspn: (libc)Search Functions.
* strdup: (libc)Copying and Concatenation.
* strdupa: (libc)Copying and Concatenation.
* strerror: (libc)Error Messages.
* strerror_r: (libc)Error Messages.
* strfmon: (libc)Formatting Numbers.
* strfry: (libc)strfry.
* strftime: (libc)Formatting Calendar Time.
* strlen: (libc)String Length.
* strncasecmp: (libc)String/Array Comparison.
* strncat: (libc)Copying and Concatenation.
* strncmp: (libc)String/Array Comparison.
* strncpy: (libc)Copying and Concatenation.
* strndup: (libc)Copying and Concatenation.
* strndupa: (libc)Copying and Concatenation.
* strnlen: (libc)String Length.
* strpbrk: (libc)Search Functions.
* strptime: (libc)Low-Level Time String Parsing.
* strrchr: (libc)Search Functions.
* strsep: (libc)Finding Tokens in a String.
* strsignal: (libc)Signal Messages.
* strspn: (libc)Search Functions.
* strstr: (libc)Search Functions.
* strtod: (libc)Parsing of Floats.
* strtof: (libc)Parsing of Floats.
* strtoimax: (libc)Parsing of Integers.
* strtok: (libc)Finding Tokens in a String.
* strtok_r: (libc)Finding Tokens in a String.
* strtol: (libc)Parsing of Integers.
* strtold: (libc)Parsing of Floats.
* strtoll: (libc)Parsing of Integers.
* strtoq: (libc)Parsing of Integers.
* strtoul: (libc)Parsing of Integers.
* strtoull: (libc)Parsing of Integers.
* strtoumax: (libc)Parsing of Integers.
* strtouq: (libc)Parsing of Integers.
* strverscmp: (libc)String/Array Comparison.
* strxfrm: (libc)Collation Functions.
* stty: (libc)BSD Terminal Modes.
* swapcontext: (libc)System V contexts.
* swprintf: (libc)Formatted Output Functions.
* swscanf: (libc)Formatted Input Functions.
* symlink: (libc)Symbolic Links.
* sync: (libc)Synchronizing I/O.
* syscall: (libc)System Calls.
* sysconf: (libc)Sysconf Definition.
* sysctl: (libc)System Parameters.
* syslog: (libc)syslog; vsyslog.
* system: (libc)Running a Command.
* sysv_signal: (libc)Basic Signal Handling.
* tan: (libc)Trig Functions.
* tanf: (libc)Trig Functions.
* tanh: (libc)Hyperbolic Functions.
* tanhf: (libc)Hyperbolic Functions.
* tanhl: (libc)Hyperbolic Functions.
* tanl: (libc)Trig Functions.
* tcdrain: (libc)Line Control.
* tcflow: (libc)Line Control.
* tcflush: (libc)Line Control.
* tcgetattr: (libc)Mode Functions.
* tcgetpgrp: (libc)Terminal Access Functions.
* tcgetsid: (libc)Terminal Access Functions.
* tcsendbreak: (libc)Line Control.
* tcsetattr: (libc)Mode Functions.
* tcsetpgrp: (libc)Terminal Access Functions.
* tdelete: (libc)Tree Search Function.
* tdestroy: (libc)Tree Search Function.
* telldir: (libc)Random Access Directory.
* tempnam: (libc)Temporary Files.
* textdomain: (libc)Locating gettext catalog.
* tfind: (libc)Tree Search Function.
* tgamma: (libc)Special Functions.
* tgammaf: (libc)Special Functions.
* tgammal: (libc)Special Functions.
* time: (libc)Simple Calendar Time.
* timegm: (libc)Broken-down Time.
* timelocal: (libc)Broken-down Time.
* times: (libc)Processor Time.
* tmpfile64: (libc)Temporary Files.
* tmpfile: (libc)Temporary Files.
* tmpnam: (libc)Temporary Files.
* tmpnam_r: (libc)Temporary Files.
* toascii: (libc)Case Conversion.
* tolower: (libc)Case Conversion.
* toupper: (libc)Case Conversion.
* towctrans: (libc)Wide Character Case Conversion.
* towlower: (libc)Wide Character Case Conversion.
* towupper: (libc)Wide Character Case Conversion.
* trunc: (libc)Rounding Functions.
* truncate64: (libc)File Size.
* truncate: (libc)File Size.
* truncf: (libc)Rounding Functions.
* truncl: (libc)Rounding Functions.
* tsearch: (libc)Tree Search Function.
* ttyname: (libc)Is It a Terminal.
* ttyname_r: (libc)Is It a Terminal.
* twalk: (libc)Tree Search Function.
* tzset: (libc)Time Zone Functions.
* ulimit: (libc)Limits on Resources.
* umask: (libc)Setting Permissions.
* umount2: (libc)Mount-Unmount-Remount.
* umount: (libc)Mount-Unmount-Remount.
* uname: (libc)Platform Type.
* ungetc: (libc)How Unread.
* ungetwc: (libc)How Unread.
* unlink: (libc)Deleting Files.
* unlockpt: (libc)Allocation.
* unsetenv: (libc)Environment Access.
* updwtmp: (libc)Manipulating the Database.
* utime: (libc)File Times.
* utimes: (libc)File Times.
* utmpname: (libc)Manipulating the Database.
* utmpxname: (libc)XPG Functions.
* va_arg: (libc)Argument Macros.
* va_copy: (libc)Argument Macros.
* va_end: (libc)Argument Macros.
* va_start: (libc)Argument Macros.
* valloc: (libc)Aligned Memory Blocks.
* vasprintf: (libc)Variable Arguments Output.
* verr: (libc)Error Messages.
* verrx: (libc)Error Messages.
* versionsort64: (libc)Scanning Directory Content.
* versionsort: (libc)Scanning Directory Content.
* vfork: (libc)Creating a Process.
* vfprintf: (libc)Variable Arguments Output.
* vfscanf: (libc)Variable Arguments Input.
* vfwprintf: (libc)Variable Arguments Output.
* vfwscanf: (libc)Variable Arguments Input.
* vlimit: (libc)Limits on Resources.
* vprintf: (libc)Variable Arguments Output.
* vscanf: (libc)Variable Arguments Input.
* vsnprintf: (libc)Variable Arguments Output.
* vsprintf: (libc)Variable Arguments Output.
* vsscanf: (libc)Variable Arguments Input.
* vswprintf: (libc)Variable Arguments Output.
* vswscanf: (libc)Variable Arguments Input.
* vsyslog: (libc)syslog; vsyslog.
* vtimes: (libc)Resource Usage.
* vwarn: (libc)Error Messages.
* vwarnx: (libc)Error Messages.
* vwprintf: (libc)Variable Arguments Output.
* vwscanf: (libc)Variable Arguments Input.
* wait3: (libc)BSD Wait Functions.
* wait4: (libc)Process Completion.
* wait: (libc)Process Completion.
* waitpid: (libc)Process Completion.
* warn: (libc)Error Messages.
* warnx: (libc)Error Messages.
* wcpcpy: (libc)Copying and Concatenation.
* wcpncpy: (libc)Copying and Concatenation.
* wcrtomb: (libc)Converting a Character.
* wcscasecmp: (libc)String/Array Comparison.
* wcscat: (libc)Copying and Concatenation.
* wcschr: (libc)Search Functions.
* wcschrnul: (libc)Search Functions.
* wcscmp: (libc)String/Array Comparison.
* wcscoll: (libc)Collation Functions.
* wcscpy: (libc)Copying and Concatenation.
* wcscspn: (libc)Search Functions.
* wcsdup: (libc)Copying and Concatenation.
* wcsftime: (libc)Formatting Calendar Time.
* wcslen: (libc)String Length.
* wcsncasecmp: (libc)String/Array Comparison.
* wcsncat: (libc)Copying and Concatenation.
* wcsncmp: (libc)String/Array Comparison.
* wcsncpy: (libc)Copying and Concatenation.
* wcsnlen: (libc)String Length.
* wcsnrtombs: (libc)Converting Strings.
* wcspbrk: (libc)Search Functions.
* wcsrchr: (libc)Search Functions.
* wcsrtombs: (libc)Converting Strings.
* wcsspn: (libc)Search Functions.
* wcsstr: (libc)Search Functions.
* wcstod: (libc)Parsing of Floats.
* wcstof: (libc)Parsing of Floats.
* wcstoimax: (libc)Parsing of Integers.
* wcstok: (libc)Finding Tokens in a String.
* wcstol: (libc)Parsing of Integers.
* wcstold: (libc)Parsing of Floats.
* wcstoll: (libc)Parsing of Integers.
* wcstombs: (libc)Non-reentrant String Conversion.
* wcstoq: (libc)Parsing of Integers.
* wcstoul: (libc)Parsing of Integers.
* wcstoull: (libc)Parsing of Integers.
* wcstoumax: (libc)Parsing of Integers.
* wcstouq: (libc)Parsing of Integers.
* wcswcs: (libc)Search Functions.
* wcsxfrm: (libc)Collation Functions.
* wctob: (libc)Converting a Character.
* wctomb: (libc)Non-reentrant Character Conversion.
* wctrans: (libc)Wide Character Case Conversion.
* wctype: (libc)Classification of Wide Characters.
* wmemchr: (libc)Search Functions.
* wmemcmp: (libc)String/Array Comparison.
* wmemcpy: (libc)Copying and Concatenation.
* wmemmove: (libc)Copying and Concatenation.
* wmempcpy: (libc)Copying and Concatenation.
* wmemset: (libc)Copying and Concatenation.
* wordexp: (libc)Calling Wordexp.
* wordfree: (libc)Calling Wordexp.
* wprintf: (libc)Formatted Output Functions.
* write: (libc)I/O Primitives.
* writev: (libc)Scatter-Gather.
* wscanf: (libc)Formatted Input Functions.
* y0: (libc)Special Functions.
* y0f: (libc)Special Functions.
* y0l: (libc)Special Functions.
* y1: (libc)Special Functions.
* y1f: (libc)Special Functions.
* y1l: (libc)Special Functions.
* yn: (libc)Special Functions.
* ynf: (libc)Special Functions.
* ynl: (libc)Special Functions.

File:, Node: Non-reentrant String Conversion, Next: Shift State, Prev: Non-reentrant Character Conversion, Up: Non-reentrant Conversion
6.4.2 Non-reentrant Conversion of Strings
For convenience the ISO C90 standard also defines functions to convert
entire strings instead of single characters. These functions suffer
from the same problems as their reentrant counterparts from Amendment 1
to ISO C90; see *note Converting Strings::.
-- Function: size_t mbstowcs (wchar_t *WSTRING, const char *STRING,
size_t SIZE)
Preliminary: | MT-Safe | AS-Unsafe corrupt heap lock dlopen |
AC-Unsafe corrupt lock mem fd | *Note POSIX Safety Concepts::.
The 'mbstowcs' ("multibyte string to wide character string")
function converts the null-terminated string of multibyte
characters STRING to an array of wide character codes, storing not
more than SIZE wide characters into the array beginning at WSTRING.
The terminating null character counts towards the size, so if SIZE
is less than the actual number of wide characters resulting from
STRING, no terminating null character is stored.
The conversion of characters from STRING begins in the initial
shift state.
If an invalid multibyte character sequence is found, the 'mbstowcs'
function returns a value of -1. Otherwise, it returns the number
of wide characters stored in the array WSTRING. This number does
not include the terminating null character, which is present if the
number is less than SIZE.
Here is an example showing how to convert a string of multibyte
characters, allocating enough space for the result.
wchar_t *
mbstowcs_alloc (const char *string)
size_t size = strlen (string) + 1;
wchar_t *buf = xmalloc (size * sizeof (wchar_t));
size = mbstowcs (buf, string, size);
if (size == (size_t) -1)
return NULL;
buf = xrealloc (buf, (size + 1) * sizeof (wchar_t));
return buf;
-- Function: size_t wcstombs (char *STRING, const wchar_t *WSTRING,
size_t SIZE)
Preliminary: | MT-Safe | AS-Unsafe corrupt heap lock dlopen |
AC-Unsafe corrupt lock mem fd | *Note POSIX Safety Concepts::.
The 'wcstombs' ("wide character string to multibyte string")
function converts the null-terminated wide character array WSTRING
into a string containing multibyte characters, storing not more
than SIZE bytes starting at STRING, followed by a terminating null
character if there is room. The conversion of characters begins in
the initial shift state.
The terminating null character counts towards the size, so if SIZE
is less than or equal to the number of bytes needed in WSTRING, no
terminating null character is stored.
If a code that does not correspond to a valid multibyte character
is found, the 'wcstombs' function returns a value of -1.
Otherwise, the return value is the number of bytes stored in the
array STRING. This number does not include the terminating null
character, which is present if the number is less than SIZE.

File:, Node: Shift State, Prev: Non-reentrant String Conversion, Up: Non-reentrant Conversion
6.4.3 States in Non-reentrant Functions
In some multibyte character codes, the _meaning_ of any particular byte
sequence is not fixed; it depends on what other sequences have come
earlier in the same string. Typically there are just a few sequences
that can change the meaning of other sequences; these few are called
"shift sequences" and we say that they set the "shift state" for other
sequences that follow.
To illustrate shift state and shift sequences, suppose we decide that
the sequence '0200' (just one byte) enters Japanese mode, in which pairs
of bytes in the range from '0240' to '0377' are single characters, while
'0201' enters Latin-1 mode, in which single bytes in the range from
'0240' to '0377' are characters, and interpreted according to the ISO
Latin-1 character set. This is a multibyte code that has two
alternative shift states ("Japanese mode" and "Latin-1 mode"), and two
shift sequences that specify particular shift states.
When the multibyte character code in use has shift states, then
'mblen', 'mbtowc', and 'wctomb' must maintain and update the current
shift state as they scan the string. To make this work properly, you
must follow these rules:
* Before starting to scan a string, call the function with a null
pointer for the multibyte character address--for example, 'mblen
(NULL, 0)'. This initializes the shift state to its standard
initial value.
* Scan the string one character at a time, in order. Do not "back
up" and rescan characters already scanned, and do not intersperse
the processing of different strings.
Here is an example of using 'mblen' following these rules:
scan_string (char *s)
int length = strlen (s);
/* Initialize shift state. */
mblen (NULL, 0);
while (1)
int thischar = mblen (s, length);
/* Deal with end of string and invalid characters. */
if (thischar == 0)
if (thischar == -1)
error ("invalid multibyte character");
/* Advance past this character. */
s += thischar;
length -= thischar;
The functions 'mblen', 'mbtowc' and 'wctomb' are not reentrant when
using a multibyte code that uses a shift state. However, no other
library functions call these functions, so you don't have to worry that
the shift state will be changed mysteriously.

File:, Node: Generic Charset Conversion, Prev: Non-reentrant Conversion, Up: Character Set Handling
6.5 Generic Charset Conversion
The conversion functions mentioned so far in this chapter all had in
common that they operate on character sets that are not directly
specified by the functions. The multibyte encoding used is specified by
the currently selected locale for the 'LC_CTYPE' category. The wide
character set is fixed by the implementation (in the case of the GNU C
Library it is always UCS-4 encoded ISO 10646.
This has of course several problems when it comes to general
character conversion:
* For every conversion where neither the source nor the destination
character set is the character set of the locale for the 'LC_CTYPE'
category, one has to change the 'LC_CTYPE' locale using
Changing the 'LC_CTYPE' locale introduces major problems for the
rest of the programs since several more functions (e.g., the
character classification functions, *note Classification of
Characters::) use the 'LC_CTYPE' category.
* Parallel conversions to and from different character sets are not
possible since the 'LC_CTYPE' selection is global and shared by all
* If neither the source nor the destination character set is the
character set used for 'wchar_t' representation, there is at least
a two-step process necessary to convert a text using the functions
above. One would have to select the source character set as the
multibyte encoding, convert the text into a 'wchar_t' text, select
the destination character set as the multibyte encoding, and
convert the wide character text to the multibyte (= destination)
character set.
Even if this is possible (which is not guaranteed) it is a very
tiring work. Plus it suffers from the other two raised points even
more due to the steady changing of the locale.
The XPG2 standard defines a completely new set of functions, which
has none of these limitations. They are not at all coupled to the
selected locales, and they have no constraints on the character sets
selected for source and destination. Only the set of available
conversions limits them. The standard does not specify that any
conversion at all must be available. Such availability is a measure of
the quality of the implementation.
In the following text first the interface to 'iconv' and then the
conversion function, will be described. Comparisons with other
implementations will show what obstacles stand in the way of portable
applications. Finally, the implementation is described in so far as
might interest the advanced user who wants to extend conversion
* Menu:
* Generic Conversion Interface:: Generic Character Set Conversion Interface.
* iconv Examples:: A complete 'iconv' example.
* Other iconv Implementations:: Some Details about other 'iconv'
* glibc iconv Implementation:: The 'iconv' Implementation in the GNU C

File:, Node: Generic Conversion Interface, Next: iconv Examples, Up: Generic Charset Conversion
6.5.1 Generic Character Set Conversion Interface
This set of functions follows the traditional cycle of using a resource:
open-use-close. The interface consists of three functions, each of
which implements one step.
Before the interfaces are described it is necessary to introduce a
data type. Just like other open-use-close interfaces the functions
introduced here work using handles and the 'iconv.h' header defines a
special type for the handles used.
-- Data Type: iconv_t
This data type is an abstract type defined in 'iconv.h'. The user
must not assume anything about the definition of this type; it must
be completely opaque.
Objects of this type can get assigned handles for the conversions
using the 'iconv' functions. The objects themselves need not be
freed, but the conversions for which the handles stand for have to.
The first step is the function to create a handle.
-- Function: iconv_t iconv_open (const char *TOCODE, const char
Preliminary: | MT-Safe locale | AS-Unsafe corrupt heap lock dlopen
| AC-Unsafe corrupt lock mem fd | *Note POSIX Safety Concepts::.
The 'iconv_open' function has to be used before starting a
conversion. The two parameters this function takes determine the
source and destination character set for the conversion, and if the
implementation has the possibility to perform such a conversion,
the function returns a handle.
If the wanted conversion is not available, the 'iconv_open'
function returns '(iconv_t) -1'. In this case the global variable
'errno' can have the following values:
The process already has 'OPEN_MAX' file descriptors open.
The system limit of open file is reached.
Not enough memory to carry out the operation.
The conversion from FROMCODE to TOCODE is not supported.
It is not possible to use the same descriptor in different threads
to perform independent conversions. The data structures associated
with the descriptor include information about the conversion state.
This must not be messed up by using it in different conversions.
An 'iconv' descriptor is like a file descriptor as for every use a
new descriptor must be created. The descriptor does not stand for
all of the conversions from FROMSET to TOSET.
The GNU C Library implementation of 'iconv_open' has one
significant extension to other implementations. To ease the
extension of the set of available conversions, the implementation
allows storing the necessary files with data and code in an
arbitrary number of directories. How this extension must be
written will be explained below (*note glibc iconv
Implementation::). Here it is only important to say that all
directories mentioned in the 'GCONV_PATH' environment variable are
considered only if they contain a file 'gconv-modules'. These
directories need not necessarily be created by the system
administrator. In fact, this extension is introduced to help users
writing and using their own, new conversions. Of course, this does
not work for security reasons in SUID binaries; in this case only
the system directory is considered and this normally is
'PREFIX/lib/gconv'. The 'GCONV_PATH' environment variable is
examined exactly once at the first call of the 'iconv_open'
function. Later modifications of the variable have no effect.
The 'iconv_open' function was introduced early in the X/Open
Portability Guide, version 2. It is supported by all commercial
Unices as it is required for the Unix branding. However, the
quality and completeness of the implementation varies widely. The
'iconv_open' function is declared in 'iconv.h'.
The 'iconv' implementation can associate large data structure with
the handle returned by 'iconv_open'. Therefore, it is crucial to free
all the resources once all conversions are carried out and the
conversion is not needed anymore.
-- Function: int iconv_close (iconv_t CD)
Preliminary: | MT-Safe | AS-Unsafe corrupt heap lock dlopen |
AC-Unsafe corrupt lock mem | *Note POSIX Safety Concepts::.
The 'iconv_close' function frees all resources associated with the
handle CD, which must have been returned by a successful call to
the 'iconv_open' function.
If the function call was successful the return value is 0.
Otherwise it is -1 and 'errno' is set appropriately. Defined error
The conversion descriptor is invalid.
The 'iconv_close' function was introduced together with the rest of
the 'iconv' functions in XPG2 and is declared in 'iconv.h'.
The standard defines only one actual conversion function. This has,
therefore, the most general interface: it allows conversion from one
buffer to another. Conversion from a file to a buffer, vice versa, or
even file to file can be implemented on top of it.
-- Function: size_t iconv (iconv_t CD, char **INBUF, size_t
Preliminary: | MT-Safe race:cd | AS-Safe | AC-Unsafe corrupt |
*Note POSIX Safety Concepts::.
The 'iconv' function converts the text in the input buffer
according to the rules associated with the descriptor CD and stores
the result in the output buffer. It is possible to call the
function for the same text several times in a row since for
stateful character sets the necessary state information is kept in
the data structures associated with the descriptor.
The input buffer is specified by '*INBUF' and it contains
'*INBYTESLEFT' bytes. The extra indirection is necessary for
communicating the used input back to the caller (see below). It is
important to note that the buffer pointer is of type 'char' and the
length is measured in bytes even if the input text is encoded in
wide characters.
The output buffer is specified in a similar way. '*OUTBUF' points
to the beginning of the buffer with at least '*OUTBYTESLEFT' bytes
room for the result. The buffer pointer again is of type 'char'
and the length is measured in bytes. If OUTBUF or '*OUTBUF' is a
null pointer, the conversion is performed but no output is
If INBUF is a null pointer, the 'iconv' function performs the
necessary action to put the state of the conversion into the
initial state. This is obviously a no-op for non-stateful
encodings, but if the encoding has a state, such a function call
might put some byte sequences in the output buffer, which perform
the necessary state changes. The next call with INBUF not being a
null pointer then simply goes on from the initial state. It is
important that the programmer never makes any assumption as to
whether the conversion has to deal with states. Even if the input
and output character sets are not stateful, the implementation
might still have to keep states. This is due to the implementation
chosen for the GNU C Library as it is described below. Therefore
an 'iconv' call to reset the state should always be performed if
some protocol requires this for the output text.
The conversion stops for one of three reasons. The first is that
all characters from the input buffer are converted. This actually
can mean two things: either all bytes from the input buffer are
consumed or there are some bytes at the end of the buffer that
possibly can form a complete character but the input is incomplete.
The second reason for a stop is that the output buffer is full.
And the third reason is that the input contains invalid characters.
In all of these cases the buffer pointers after the last successful
conversion, for input and output buffer, are stored in INBUF and
OUTBUF, and the available room in each buffer is stored in
Since the character sets selected in the 'iconv_open' call can be
almost arbitrary, there can be situations where the input buffer
contains valid characters, which have no identical representation
in the output character set. The behavior in this situation is
undefined. The _current_ behavior of the GNU C Library in this
situation is to return with an error immediately. This certainly
is not the most desirable solution; therefore, future versions will
provide better ones, but they are not yet finished.
If all input from the input buffer is successfully converted and
stored in the output buffer, the function returns the number of
non-reversible conversions performed. In all other cases the
return value is '(size_t) -1' and 'errno' is set appropriately. In
such cases the value pointed to by INBYTESLEFT is nonzero.
The conversion stopped because of an invalid byte sequence in
the input. After the call, '*INBUF' points at the first byte
of the invalid byte sequence.
The conversion stopped because it ran out of space in the
output buffer.
The conversion stopped because of an incomplete byte sequence
at the end of the input buffer.
The CD argument is invalid.
The 'iconv' function was introduced in the XPG2 standard and is
declared in the 'iconv.h' header.
The definition of the 'iconv' function is quite good overall. It
provides quite flexible functionality. The only problems lie in the
boundary cases, which are incomplete byte sequences at the end of the
input buffer and invalid input. A third problem, which is not really a
design problem, is the way conversions are selected. The standard does
not say anything about the legitimate names, a minimal set of available
conversions. We will see how this negatively impacts other
implementations, as demonstrated below.

File:, Node: iconv Examples, Next: Other iconv Implementations, Prev: Generic Conversion Interface, Up: Generic Charset Conversion
6.5.2 A complete 'iconv' example
The example below features a solution for a common problem. Given that
one knows the internal encoding used by the system for 'wchar_t'
strings, one often is in the position to read text from a file and store
it in wide character buffers. One can do this using 'mbsrtowcs', but
then we run into the problems discussed above.
file2wcs (int fd, const char *charset, wchar_t *outbuf, size_t avail)
char inbuf[BUFSIZ];
size_t insize = 0;
char *wrptr = (char *) outbuf;
int result = 0;
iconv_t cd;
cd = iconv_open ("WCHAR_T", charset);
if (cd == (iconv_t) -1)
/* Something went wrong. */
if (errno == EINVAL)
error (0, 0, "conversion from '%s' to wchar_t not available",
perror ("iconv_open");
/* Terminate the output string. */
*outbuf = L'\0';
return -1;
while (avail > 0)
size_t nread;
size_t nconv;
char *inptr = inbuf;
/* Read more input. */
nread = read (fd, inbuf + insize, sizeof (inbuf) - insize);
if (nread == 0)
/* When we come here the file is completely read.
This still could mean there are some unused
characters in the 'inbuf'. Put them back. */
if (lseek (fd, -insize, SEEK_CUR) == -1)
result = -1;
/* Now write out the byte sequence to get into the
initial state if this is necessary. */
iconv (cd, NULL, NULL, &wrptr, &avail);
insize += nread;
/* Do the conversion. */
nconv = iconv (cd, &inptr, &insize, &wrptr, &avail);
if (nconv == (size_t) -1)
/* Not everything went right. It might only be
an unfinished byte sequence at the end of the
buffer. Or it is a real problem. */
if (errno == EINVAL)
/* This is harmless. Simply move the unused
bytes to the beginning of the buffer so that
they can be used in the next round. */
memmove (inbuf, inptr, insize);
/* It is a real problem. Maybe we ran out of
space in the output buffer or we have invalid
input. In any case back the file pointer to
the position of the last processed byte. */
lseek (fd, -insize, SEEK_CUR);
result = -1;
/* Terminate the output string. */
if (avail >= sizeof (wchar_t))
*((wchar_t *) wrptr) = L'\0';
if (iconv_close (cd) != 0)
perror ("iconv_close");
return (wchar_t *) wrptr - outbuf;
This example shows the most important aspects of using the 'iconv'
functions. It shows how successive calls to 'iconv' can be used to
convert large amounts of text. The user does not have to care about
stateful encodings as the functions take care of everything.
An interesting point is the case where 'iconv' returns an error and
'errno' is set to 'EINVAL'. This is not really an error in the
transformation. It can happen whenever the input character set contains
byte sequences of more than one byte for some character and texts are
not processed in one piece. In this case there is a chance that a
multibyte sequence is cut. The caller can then simply read the
remainder of the takes and feed the offending bytes together with new
character from the input to 'iconv' and continue the work. The internal
state kept in the descriptor is _not_ unspecified after such an event as
is the case with the conversion functions from the ISO C standard.
The example also shows the problem of using wide character strings
with 'iconv'. As explained in the description of the 'iconv' function
above, the function always takes a pointer to a 'char' array and the
available space is measured in bytes. In the example, the output buffer
is a wide character buffer; therefore, we use a local variable WRPTR of
type 'char *', which is used in the 'iconv' calls.
This looks rather innocent but can lead to problems on platforms that
have tight restriction on alignment. Therefore the caller of 'iconv'
has to make sure that the pointers passed are suitable for access of
characters from the appropriate character set. Since, in the above
case, the input parameter to the function is a 'wchar_t' pointer, this
is the case (unless the user violates alignment when computing the
parameter). But in other situations, especially when writing generic
functions where one does not know what type of character set one uses
and, therefore, treats text as a sequence of bytes, it might become

File:, Node: Other iconv Implementations, Next: glibc iconv Implementation, Prev: iconv Examples, Up: Generic Charset Conversion
6.5.3 Some Details about other 'iconv' Implementations
This is not really the place to discuss the 'iconv' implementation of
other systems but it is necessary to know a bit about them to write
portable programs. The above mentioned problems with the specification
of the 'iconv' functions can lead to portability issues.
The first thing to notice is that, due to the large number of
character sets in use, it is certainly not practical to encode the
conversions directly in the C library. Therefore, the conversion
information must come from files outside the C library. This is usually
done in one or both of the following ways:
* The C library contains a set of generic conversion functions that
can read the needed conversion tables and other information from
data files. These files get loaded when necessary.
This solution is problematic as it requires a great deal of effort
to apply to all character sets (potentially an infinite set). The
differences in the structure of the different character sets is so
large that many different variants of the table-processing
functions must be developed. In addition, the generic nature of
these functions make them slower than specifically implemented
* The C library only contains a framework that can dynamically load
object files and execute the conversion functions contained
This solution provides much more flexibility. The C library itself
contains only very little code and therefore reduces the general
memory footprint. Also, with a documented interface between the C
library and the loadable modules it is possible for third parties
to extend the set of available conversion modules. A drawback of
this solution is that dynamic loading must be available.
Some implementations in commercial Unices implement a mixture of
these possibilities; the majority implement only the second solution.
Using loadable modules moves the code out of the library itself and
keeps the door open for extensions and improvements, but this design is
also limiting on some platforms since not many platforms support dynamic
loading in statically linked programs. On platforms without this
capability it is therefore not possible to use this interface in
statically linked programs. The GNU C Library has, on ELF platforms, no
problems with dynamic loading in these situations; therefore, this point
is moot. The danger is that one gets acquainted with this situation and
forgets about the restrictions on other systems.
A second thing to know about other 'iconv' implementations is that
the number of available conversions is often very limited. Some
implementations provide, in the standard release (not special
international or developer releases), at most 100 to 200 conversion
possibilities. This does not mean 200 different character sets are
supported; for example, conversions from one character set to a set of
10 others might count as 10 conversions. Together with the other
direction this makes 20 conversion possibilities used up by one
character set. One can imagine the thin coverage these platform
provide. Some Unix vendors even provide only a handful of conversions,
which renders them useless for almost all uses.
This directly leads to a third and probably the most problematic
point. The way the 'iconv' conversion functions are implemented on all
known Unix systems and the availability of the conversion functions from
character set A to B and the conversion from B to C does _not_ imply
that the conversion from A to C is available.
This might not seem unreasonable and problematic at first, but it is
a quite big problem as one will notice shortly after hitting it. To
show the problem we assume to write a program that has to convert from A
to C. A call like
cd = iconv_open ("C", "A");
fails according to the assumption above. But what does the program do
now? The conversion is necessary; therefore, simply giving up is not an
This is a nuisance. The 'iconv' function should take care of this.
But how should the program proceed from here on? If it tries to convert
to character set B, first the two 'iconv_open' calls
cd1 = iconv_open ("B", "A");
cd2 = iconv_open ("C", "B");
will succeed, but how to find B?
Unfortunately, the answer is: there is no general solution. On some
systems guessing might help. On those systems most character sets can
convert to and from UTF-8 encoded ISO 10646 or Unicode text. Beside
this only some very system-specific methods can help. Since the
conversion functions come from loadable modules and these modules must
be stored somewhere in the filesystem, one _could_ try to find them and
determine from the available file which conversions are available and
whether there is an indirect route from A to C.
This example shows one of the design errors of 'iconv' mentioned
above. It should at least be possible to determine the list of
available conversion programmatically so that if 'iconv_open' says there
is no such conversion, one could make sure this also is true for
indirect routes.

File:, Node: glibc iconv Implementation, Prev: Other iconv Implementations, Up: Generic Charset Conversion
6.5.4 The 'iconv' Implementation in the GNU C Library
After reading about the problems of 'iconv' implementations in the last
section it is certainly good to note that the implementation in the GNU
C Library has none of the problems mentioned above. What follows is a
step-by-step analysis of the points raised above. The evaluation is
based on the current state of the development (as of January 1999). The
development of the 'iconv' functions is not complete, but basic
functionality has solidified.
The GNU C Library's 'iconv' implementation uses shared loadable
modules to implement the conversions. A very small number of
conversions are built into the library itself but these are only rather
trivial conversions.
All the benefits of loadable modules are available in the GNU C
Library implementation. This is especially appealing since the
interface is well documented (see below), and it, therefore, is easy to
write new conversion modules. The drawback of using loadable objects is
not a problem in the GNU C Library, at least on ELF systems. Since the
library is able to load shared objects even in statically linked
binaries, static linking need not be forbidden in case one wants to use
The second mentioned problem is the number of supported conversions.
Currently, the GNU C Library supports more than 150 character sets. The
way the implementation is designed the number of supported conversions
is greater than 22350 (150 times 149). If any conversion from or to a
character set is missing, it can be added easily.
Particularly impressive as it may be, this high number is due to the
fact that the GNU C Library implementation of 'iconv' does not have the
third problem mentioned above (i.e., whenever there is a conversion from
a character set A to B and from B to C it is always possible to convert
from A to C directly). If the 'iconv_open' returns an error and sets
'errno' to 'EINVAL', there is no known way, directly or indirectly, to
perform the wanted conversion.
Triangulation is achieved by providing for each character set a
conversion from and to UCS-4 encoded ISO 10646. Using ISO 10646 as an
intermediate representation it is possible to "triangulate" (i.e.,
convert with an intermediate representation).
There is no inherent requirement to provide a conversion to ISO 10646
for a new character set, and it is also possible to provide other
conversions where neither source nor destination character set is
ISO 10646. The existing set of conversions is simply meant to cover all
conversions that might be of interest.
All currently available conversions use the triangulation method
above, making conversion run unnecessarily slow. If, for example,
somebody often needs the conversion from ISO-2022-JP to EUC-JP, a
quicker solution would involve direct conversion between the two
character sets, skipping the input to ISO 10646 first. The two
character sets of interest are much more similar to each other than to
ISO 10646.
In such a situation one easily can write a new conversion and provide
it as a better alternative. The GNU C Library 'iconv' implementation
would automatically use the module implementing the conversion if it is
specified to be more efficient. Format of 'gconv-modules' files
All information about the available conversions comes from a file named
'gconv-modules', which can be found in any of the directories along the
'GCONV_PATH'. The 'gconv-modules' files are line-oriented text files,
where each of the lines has one of the following formats:
* If the first non-whitespace character is a '#' the line contains
only comments and is ignored.
* Lines starting with 'alias' define an alias name for a character
set. Two more words are expected on the line. The first word
defines the alias name, and the second defines the original name of
the character set. The effect is that it is possible to use the
alias name in the FROMSET or TOSET parameters of 'iconv_open' and
achieve the same result as when using the real character set name.
This is quite important as a character set has often many different
names. There is normally an official name but this need not
correspond to the most popular name. Beside this many character
sets have special names that are somehow constructed. For example,
all character sets specified by the ISO have an alias of the form
'ISO-IR-NNN' where NNN is the registration number. This allows
programs that know about the registration number to construct
character set names and use them in 'iconv_open' calls. More on
the available names and aliases follows below.
* Lines starting with 'module' introduce an available conversion
module. These lines must contain three or four more words.
The first word specifies the source character set, the second word
the destination character set of conversion implemented in this
module, and the third word is the name of the loadable module. The
filename is constructed by appending the usual shared object suffix
(normally '.so') and this file is then supposed to be found in the
same directory the 'gconv-modules' file is in. The last word on
the line, which is optional, is a numeric value representing the
cost of the conversion. If this word is missing, a cost of 1 is
assumed. The numeric value itself does not matter that much; what
counts are the relative values of the sums of costs for all
possible conversion paths. Below is a more precise description of
the use of the cost value.
Returning to the example above where one has written a module to
directly convert from ISO-2022-JP to EUC-JP and back. All that has to
be done is to put the new module, let its name be, in
a directory and add a file 'gconv-modules' with the following content in
the same directory:
module ISO-2022-JP// EUC-JP// ISO2022JP-EUCJP 1
module EUC-JP// ISO-2022-JP// ISO2022JP-EUCJP 1
To see why this is sufficient, it is necessary to understand how the
conversion used by 'iconv' (and described in the descriptor) is
selected. The approach to this problem is quite simple.
At the first call of the 'iconv_open' function the program reads all
available 'gconv-modules' files and builds up two tables: one containing
all the known aliases and another that contains the information about
the conversions and which shared object implements them. Finding the conversion path in 'iconv'
The set of available conversions form a directed graph with weighted
edges. The weights on the edges are the costs specified in the
'gconv-modules' files. The 'iconv_open' function uses an algorithm
suitable for search for the best path in such a graph and so constructs
a list of conversions that must be performed in succession to get the
transformation from the source to the destination character set.
Explaining why the above 'gconv-modules' files allows the 'iconv'
implementation to resolve the specific ISO-2022-JP to EUC-JP conversion
module instead of the conversion coming with the library itself is
straightforward. Since the latter conversion takes two steps (from
ISO-2022-JP to ISO 10646 and then from ISO 10646 to EUC-JP), the cost is
1+1 = 2. The above 'gconv-modules' file, however, specifies that the
new conversion modules can perform this conversion with only the cost of
A mysterious item about the 'gconv-modules' file above (and also the
file coming with the GNU C Library) are the names of the character sets
specified in the 'module' lines. Why do almost all the names end in
'//'? And this is not all: the names can actually be regular
expressions. At this point in time this mystery should not be revealed,
unless you have the relevant spell-casting materials: ashes from an
original DOS 6.2 boot disk burnt in effigy, a crucifix blessed by St.
Emacs, assorted herbal roots from Central America, sand from Cebu, etc.
Sorry! *The part of the implementation where this is used is not yet
finished. For now please simply follow the existing examples. It'll
become clearer once it is. -drepper*
A last remark about the 'gconv-modules' is about the names not ending
with '//'. A character set named 'INTERNAL' is often mentioned. From
the discussion above and the chosen name it should have become clear
that this is the name for the representation used in the intermediate
step of the triangulation. We have said that this is UCS-4 but actually
that is not quite right. The UCS-4 specification also includes the
specification of the byte ordering used. Since a UCS-4 value consists
of four bytes, a stored value is affected by byte ordering. The
internal representation is _not_ the same as UCS-4 in case the byte
ordering of the processor (or at least the running process) is not the
same as the one required for UCS-4. This is done for performance
reasons as one does not want to perform unnecessary byte-swapping
operations if one is not interested in actually seeing the result in
UCS-4. To avoid trouble with endianness, the internal representation
consistently is named 'INTERNAL' even on big-endian systems where the
representations are identical. 'iconv' module data structures
So far this section has described how modules are located and considered
to be used. What remains to be described is the interface of the
modules so that one can write new ones. This section describes the
interface as it is in use in January 1999. The interface will change a
bit in the future but, with luck, only in an upwardly compatible way.
The definitions necessary to write new modules are publicly available
in the non-standard header 'gconv.h'. The following text, therefore,
describes the definitions from this header file. First, however, it is
necessary to get an overview.
From the perspective of the user of 'iconv' the interface is quite
simple: the 'iconv_open' function returns a handle that can be used in
calls to 'iconv', and finally the handle is freed with a call to
'iconv_close'. The problem is that the handle has to be able to
represent the possibly long sequences of conversion steps and also the
state of each conversion since the handle is all that is passed to the
'iconv' function. Therefore, the data structures are really the
elements necessary to understanding the implementation.
We need two different kinds of data structures. The first describes
the conversion and the second describes the state etc. There are really
two type definitions like this in 'gconv.h'.
-- Data type: struct __gconv_step
This data structure describes one conversion a module can perform.
For each function in a loaded module with conversion functions
there is exactly one object of this type. This object is shared by
all users of the conversion (i.e., this object does not contain any
information corresponding to an actual conversion; it only
describes the conversion itself).
'struct __gconv_loaded_object *__shlib_handle'
'const char *__modname'
'int __counter'
All these elements of the structure are used internally in the
C library to coordinate loading and unloading the shared. One
must not expect any of the other elements to be available or
'const char *__from_name'
'const char *__to_name'
'__from_name' and '__to_name' contain the names of the source
and destination character sets. They can be used to identify
the actual conversion to be carried out since one module might
implement conversions for more than one character set and/or
'gconv_fct __fct'
'gconv_init_fct __init_fct'
'gconv_end_fct __end_fct'
These elements contain pointers to the functions in the
loadable module. The interface will be explained below.
'int __min_needed_from'
'int __max_needed_from'
'int __min_needed_to'
'int __max_needed_to;'
These values have to be supplied in the init function of the
module. The '__min_needed_from' value specifies how many
bytes a character of the source character set at least needs.
The '__max_needed_from' specifies the maximum value that also
includes possible shift sequences.
The '__min_needed_to' and '__max_needed_to' values serve the
same purpose as '__min_needed_from' and '__max_needed_from'
but this time for the destination character set.
It is crucial that these values be accurate since otherwise
the conversion functions will have problems or not work at
'int __stateful'
This element must also be initialized by the init function.
'int __stateful' is nonzero if the source character set is
stateful. Otherwise it is zero.
'void *__data'
This element can be used freely by the conversion functions in
the module. 'void *__data' can be used to communicate extra
information from one call to another. 'void *__data' need not
be initialized if not needed at all. If 'void *__data'
element is assigned a pointer to dynamically allocated memory
(presumably in the init function) it has to be made sure that
the end function deallocates the memory. Otherwise the
application will leak memory.
It is important to be aware that this data structure is shared
by all users of this specification conversion and therefore
the '__data' element must not contain data specific to one
specific use of the conversion function.
-- Data type: struct __gconv_step_data
This is the data structure that contains the information specific
to each use of the conversion functions.
'char *__outbuf'
'char *__outbufend'
These elements specify the output buffer for the conversion
step. The '__outbuf' element points to the beginning of the
buffer, and '__outbufend' points to the byte following the
last byte in the buffer. The conversion function must not
assume anything about the size of the buffer but it can be
safely assumed the there is room for at least one complete
character in the output buffer.
Once the conversion is finished, if the conversion is the last
step, the '__outbuf' element must be modified to point after
the last byte written into the buffer to signal how much
output is available. If this conversion step is not the last
one, the element must not be modified. The '__outbufend'
element must not be modified.
'int __is_last'
This element is nonzero if this conversion step is the last
one. This information is necessary for the recursion. See
the description of the conversion function internals below.
This element must never be modified.
'int __invocation_counter'
The conversion function can use this element to see how many
calls of the conversion function already happened. Some
character sets require a certain prolog when generating
output, and by comparing this value with zero, one can find
out whether it is the first call and whether, therefore, the
prolog should be emitted. This element must never be
'int __internal_use'
This element is another one rarely used but needed in certain
situations. It is assigned a nonzero value in case the
conversion functions are used to implement 'mbsrtowcs'
(i.e., the function is not used directly through the 'iconv'
This sometimes makes a difference as it is expected that the
'iconv' functions are used to translate entire texts while the
'mbsrtowcs' functions are normally used only to convert single
strings and might be used multiple times to convert entire
But in this situation we would have problem complying with
some rules of the character set specification. Some character
sets require a prolog, which must appear exactly once for an
entire text. If a number of 'mbsrtowcs' calls are used to
convert the text, only the first call must add the prolog.
However, because there is no communication between the
different calls of 'mbsrtowcs', the conversion functions have
no possibility to find this out. The situation is different
for sequences of 'iconv' calls since the handle allows access
to the needed information.
The 'int __internal_use' element is mostly used together with
'__invocation_counter' as follows:
if (!data->__internal_use
&& data->__invocation_counter == 0)
/* Emit prolog. */
This element must never be modified.
'mbstate_t *__statep'
The '__statep' element points to an object of type 'mbstate_t'
(*note Keeping the state::). The conversion of a stateful
character set must use the object pointed to by '__statep' to
store information about the conversion state. The '__statep'
element itself must never be modified.
'mbstate_t __state'
This element must _never_ be used directly. It is only part
of this structure to have the needed space allocated. 'iconv' module interfaces
With the knowledge about the data structures we now can describe the
conversion function itself. To understand the interface a bit of
knowledge is necessary about the functionality in the C library that
loads the objects with the conversions.
It is often the case that one conversion is used more than once
(i.e., there are several 'iconv_open' calls for the same set of
character sets during one program run). The 'mbsrtowcs'
functions in the GNU C Library also use the 'iconv' functionality, which
increases the number of uses of the same functions even more.
Because of this multiple use of conversions, the modules do not get
loaded exclusively for one conversion. Instead a module once loaded can
be used by an arbitrary number of 'iconv' or 'mbsrtowcs' calls at the
same time. The splitting of the information between conversion-
function-specific information and conversion data makes this possible.
The last section showed the two data structures used to do this.
This is of course also reflected in the interface and semantics of
the functions that the modules must provide. There are three functions
that must have the following names:
The 'gconv_init' function initializes the conversion function
specific data structure. This very same object is shared by all
conversions that use this conversion and, therefore, no state
information about the conversion itself must be stored in here. If
a module implements more than one conversion, the 'gconv_init'
function will be called multiple times.
The 'gconv_end' function is responsible for freeing all resources
allocated by the 'gconv_init' function. If there is nothing to do,
this function can be missing. Special care must be taken if the
module implements more than one conversion and the 'gconv_init'
function does not allocate the same resources for all conversions.
This is the actual conversion function. It is called to convert
one block of text. It gets passed the conversion step information
initialized by 'gconv_init' and the conversion data, specific to
this use of the conversion functions.
There are three data types defined for the three module interface
functions and these define the interface.
-- Data type: int (*__gconv_init_fct) (struct __gconv_step *)
This specifies the interface of the initialization function of the
module. It is called exactly once for each conversion the module
As explained in the description of the 'struct __gconv_step' data
structure above the initialization function has to initialize parts
of it.
These elements must be initialized to the exact numbers of the
minimum and maximum number of bytes used by one character in
the source and destination character sets, respectively. If
the characters all have the same size, the minimum and maximum
values are the same.
This element must be initialized to a nonzero value if the
source character set is stateful. Otherwise it must be zero.
If the initialization function needs to communicate some
information to the conversion function, this communication can
happen using the '__data' element of the '__gconv_step' structure.
But since this data is shared by all the conversions, it must not
be modified by the conversion function. The example below shows
how this can be used.
#define MIN_NEEDED_TO 4
#define MAX_NEEDED_TO 4
gconv_init (struct __gconv_step *step)
/* Determine which direction. */
struct iso2022jp_data *new_data;
enum direction dir = illegal_dir;
enum variant var = illegal_var;
int result;
if (__strcasecmp (step->__from_name, "ISO-2022-JP//") == 0)
dir = from_iso2022jp;
var = iso2022jp;
else if (__strcasecmp (step->__to_name, "ISO-2022-JP//") == 0)
dir = to_iso2022jp;
var = iso2022jp;
else if (__strcasecmp (step->__from_name, "ISO-2022-JP-2//") == 0)
dir = from_iso2022jp;
var = iso2022jp2;
else if (__strcasecmp (step->__to_name, "ISO-2022-JP-2//") == 0)
dir = to_iso2022jp;
var = iso2022jp2;
result = __GCONV_NOCONV;
if (dir != illegal_dir)
new_data = (struct iso2022jp_data *)
malloc (sizeof (struct iso2022jp_data));
result = __GCONV_NOMEM;
if (new_data != NULL)
new_data->dir = dir;
new_data->var = var;
step->__data = new_data;
if (dir == from_iso2022jp)
step->__min_needed_from = MIN_NEEDED_FROM;
step->__max_needed_from = MAX_NEEDED_FROM;
step->__min_needed_to = MIN_NEEDED_TO;
step->__max_needed_to = MAX_NEEDED_TO;
step->__min_needed_from = MIN_NEEDED_TO;
step->__max_needed_from = MAX_NEEDED_TO;
step->__min_needed_to = MIN_NEEDED_FROM;
step->__max_needed_to = MAX_NEEDED_FROM + 2;
/* Yes, this is a stateful encoding. */
step->__stateful = 1;
result = __GCONV_OK;
return result;
The function first checks which conversion is wanted. The module
from which this function is taken implements four different
conversions; which one is selected can be determined by comparing
the names. The comparison should always be done without paying
attention to the case.
Next, a data structure, which contains the necessary information
about which conversion is selected, is allocated. The data
structure 'struct iso2022jp_data' is locally defined since, outside
the module, this data is not used at all. Please note that if all
four conversions this modules supports are requested there are four
data blocks.
One interesting thing is the initialization of the '__min_' and
'__max_' elements of the step data object. A single ISO-2022-JP
character can consist of one to four bytes. Therefore the
'MIN_NEEDED_FROM' and 'MAX_NEEDED_FROM' macros are defined this
way. The output is always the 'INTERNAL' character set (aka UCS-4)
and therefore each character consists of exactly four bytes. For
the conversion from 'INTERNAL' to ISO-2022-JP we have to take into
account that escape sequences might be necessary to switch the
character sets. Therefore the '__max_needed_to' element for this
direction gets assigned 'MAX_NEEDED_FROM + 2'. This takes into
account the two bytes needed for the escape sequences to single the
switching. The asymmetry in the maximum values for the two
directions can be explained easily: when reading ISO-2022-JP text,
escape sequences can be handled alone (i.e., it is not necessary to
process a real character since the effect of the escape sequence
can be recorded in the state information). The situation is
different for the other direction. Since it is in general not
known which character comes next, one cannot emit escape sequences
to change the state in advance. This means the escape sequences
that have to be emitted together with the next character.
Therefore one needs more room than only for the character itself.
The possible return values of the initialization function are:
The initialization succeeded
The requested conversion is not supported in the module. This
can happen if the 'gconv-modules' file has errors.
Memory required to store additional information could not be
The function called before the module is unloaded is significantly
easier. It often has nothing at all to do; in which case it can be left
out completely.
-- Data type: void (*__gconv_end_fct) (struct gconv_step *)
The task of this function is to free all resources allocated in the
initialization function. Therefore only the '__data' element of
the object pointed to by the argument is of interest. Continuing
the example from the initialization function, the finalization
function looks like this:
gconv_end (struct __gconv_step *data)
free (data->__data);
The most important function is the conversion function itself, which
can get quite complicated for complex character sets. But since this is
not of interest here, we will only describe a possible skeleton for the
conversion function.
-- Data type: int (*__gconv_fct) (struct __gconv_step *, struct
__gconv_step_data *, const char **, const char *, size_t *,
The conversion function can be called for two basic reason: to
convert text or to reset the state. From the description of the
'iconv' function it can be seen why the flushing mode is necessary.
What mode is selected is determined by the sixth argument, an
integer. This argument being nonzero means that flushing is
Common to both modes is where the output buffer can be found. The
information about this buffer is stored in the conversion step
data. A pointer to this information is passed as the second
argument to this function. The description of the 'struct
__gconv_step_data' structure has more information on the conversion
step data.
What has to be done for flushing depends on the source character
set. If the source character set is not stateful, nothing has to
be done. Otherwise the function has to emit a byte sequence to
bring the state object into the initial state. Once this all
happened the other conversion modules in the chain of conversions
have to get the same chance. Whether another step follows can be
determined from the '__is_last' element of the step data structure
to which the first parameter points.
The more interesting mode is when actual text has to be converted.
The first step in this case is to convert as much text as possible
from the input buffer and store the result in the output buffer.
The start of the input buffer is determined by the third argument,
which is a pointer to a pointer variable referencing the beginning
of the buffer. The fourth argument is a pointer to the byte right
after the last byte in the buffer.
The conversion has to be performed according to the current state
if the character set is stateful. The state is stored in an object
pointed to by the '__statep' element of the step data (second
argument). Once either the input buffer is empty or the output
buffer is full the conversion stops. At this point, the pointer
variable referenced by the third parameter must point to the byte
following the last processed byte (i.e., if all of the input is
consumed, this pointer and the fourth parameter have the same
What now happens depends on whether this step is the last one. If
it is the last step, the only thing that has to be done is to
update the '__outbuf' element of the step data structure to point
after the last written byte. This update gives the caller the
information on how much text is available in the output buffer. In
addition, the variable pointed to by the fifth parameter, which is
of type 'size_t', must be incremented by the number of characters
(_not bytes_) that were converted in a non-reversible way. Then,
the function can return.
In case the step is not the last one, the later conversion
functions have to get a chance to do their work. Therefore, the
appropriate conversion function has to be called. The information
about the functions is stored in the conversion data structures,
passed as the first parameter. This information and the step data
are stored in arrays, so the next element in both cases can be
found by simple pointer arithmetic:
gconv (struct __gconv_step *step, struct __gconv_step_data *data,
const char **inbuf, const char *inbufend, size_t *written,
int do_flush)
struct __gconv_step *next_step = step + 1;
struct __gconv_step_data *next_data = data + 1;
The 'next_step' pointer references the next step information and
'next_data' the next data record. The call of the next function
therefore will look similar to this:
next_step->__fct (next_step, next_data, &outerr, outbuf,
written, 0)
But this is not yet all. Once the function call returns the
conversion function might have some more to do. If the return
value of the function is '__GCONV_EMPTY_INPUT', more room is
available in the output buffer. Unless the input buffer is empty
the conversion, functions start all over again and process the rest
of the input buffer. If the return value is not
'__GCONV_EMPTY_INPUT', something went wrong and we have to recover
from this.
A requirement for the conversion function is that the input buffer
pointer (the third argument) always point to the last character
that was put in converted form into the output buffer. This is
trivially true after the conversion performed in the current step,
but if the conversion functions deeper downstream stop prematurely,
not all characters from the output buffer are consumed and,
therefore, the input buffer pointers must be backed off to the
right position.
Correcting the input buffers is easy to do if the input and output
character sets have a fixed width for all characters. In this
situation we can compute how many characters are left in the output
buffer and, therefore, can correct the input buffer pointer
appropriately with a similar computation. Things are getting
tricky if either character set has characters represented with
variable length byte sequences, and it gets even more complicated
if the conversion has to take care of the state. In these cases
the conversion has to be performed once again, from the known state
before the initial conversion (i.e., if necessary the state of the
conversion has to be reset and the conversion loop has to be
executed again). The difference now is that it is known how much
input must be created, and the conversion can stop before
converting the first unused character. Once this is done the input
buffer pointers must be updated again and the function can return.
One final thing should be mentioned. If it is necessary for the
conversion to know whether it is the first invocation (in case a
prolog has to be emitted), the conversion function should increment
the '__invocation_counter' element of the step data structure just
before returning to the caller. See the description of the 'struct
__gconv_step_data' structure above for more information on how this
can be used.
The return value must be one of the following values:
All input was consumed and there is room left in the output
No more room in the output buffer. In case this is not the
last step this value is propagated down from the call of the
next conversion function in the chain.
The input buffer is not entirely empty since it contains an
incomplete character sequence.
The following example provides a framework for a conversion
function. In case a new conversion has to be written the holes in
this implementation have to be filled and that is it.
gconv (struct __gconv_step *step, struct __gconv_step_data *data,
const char **inbuf, const char *inbufend, size_t *written,
int do_flush)
struct __gconv_step *next_step = step + 1;
struct __gconv_step_data *next_data = data + 1;
gconv_fct fct = next_step->__fct;
int status;
/* If the function is called with no input this means we have
to reset to the initial state. The possibly partly
converted input is dropped. */
if (do_flush)
status = __GCONV_OK;
/* Possible emit a byte sequence which put the state object
into the initial state. */
/* Call the steps down the chain if there are any but only
if we successfully emitted the escape sequence. */
if (status == __GCONV_OK && ! data->__is_last)
status = fct (next_step, next_data, NULL, NULL,
written, 1);
/* We preserve the initial values of the pointer variables. */
const char *inptr = *inbuf;
char *outbuf = data->__outbuf;
char *outend = data->__outbufend;
char *outptr;
/* Remember the start value for this round. */
inptr = *inbuf;
/* The outbuf buffer is empty. */
outptr = outbuf;
/* For stateful encodings the state must be safe here. */
/* Run the conversion loop. 'status' is set
appropriately afterwards. */
/* If this is the last step, leave the loop. There is
nothing we can do. */
if (data->__is_last)
/* Store information about how many bytes are
available. */
data->__outbuf = outbuf;
/* If any non-reversible conversions were performed,
add the number to '*written'. */
/* Write out all output that was produced. */
if (outbuf > outptr)
const char *outerr = data->__outbuf;
int result;
result = fct (next_step, next_data, &outerr,
outbuf, written, 0);
if (result != __GCONV_EMPTY_INPUT)
if (outerr != outbuf)
/* Reset the input buffer pointer. We
document here the complex case. */
size_t nstatus;
/* Reload the pointers. */
*inbuf = inptr;
outbuf = outptr;
/* Possibly reset the state. */
/* Redo the conversion, but this time
the end of the output buffer is at
'outerr'. */
/* Change the status. */
status = result;
/* All the output is consumed, we can make
another run if everything was ok. */
if (status == __GCONV_FULL_OUTPUT)
status = __GCONV_OK;
while (status == __GCONV_OK);
/* We finished one use of this step. */
return status;
This information should be sufficient to write new modules. Anybody
doing so should also take a look at the available source code in the GNU
C Library sources. It contains many examples of working and optimized

File:, Node: Locales, Next: Message Translation, Prev: Character Set Handling, Up: Top
7 Locales and Internationalization
Different countries and cultures have varying conventions for how to
communicate. These conventions range from very simple ones, such as the
format for representing dates and times, to very complex ones, such as
the language spoken.
"Internationalization" of software means programming it to be able to
adapt to the user's favorite conventions. In ISO C,
internationalization works by means of "locales". Each locale specifies
a collection of conventions, one convention for each purpose. The user
chooses a set of conventions by specifying a locale (via environment
All programs inherit the chosen locale as part of their environment.
Provided the programs are written to obey the choice of locale, they
will follow the conventions preferred by the user.
* Menu:
* Effects of Locale:: Actions affected by the choice of
* Choosing Locale:: How the user specifies a locale.
* Locale Categories:: Different purposes for which you can
select a locale.
* Setting the Locale:: How a program specifies the locale
with library functions.
* Standard Locales:: Locale names available on all systems.
* Locale Information:: How to access the information for the locale.
* Formatting Numbers:: A dedicated function to format numbers.
* Yes-or-No Questions:: Check a Response against the locale.

File:, Node: Effects of Locale, Next: Choosing Locale, Up: Locales
7.1 What Effects a Locale Has
Each locale specifies conventions for several purposes, including the
* What multibyte character sequences are valid, and how they are
interpreted (*note Character Set Handling::).
* Classification of which characters in the local character set are
considered alphabetic, and upper- and lower-case conversion
conventions (*note Character Handling::).
* The collating sequence for the local language and character set
(*note Collation Functions::).
* Formatting of numbers and currency amounts (*note General
* Formatting of dates and times (*note Formatting Calendar Time::).
* What language to use for output, including error messages (*note
Message Translation::).
* What language to use for user answers to yes-or-no questions (*note
Yes-or-No Questions::).
* What language to use for more complex user input. (The C library
doesn't yet help you implement this.)
Some aspects of adapting to the specified locale are handled
automatically by the library subroutines. For example, all your program
needs to do in order to use the collating sequence of the chosen locale
is to use 'strcoll' or 'strxfrm' to compare strings.
Other aspects of locales are beyond the comprehension of the library.
For example, the library can't automatically translate your program's
output messages into other languages. The only way you can support
output in the user's favorite language is to program this more or less
by hand. The C library provides functions to handle translations for
multiple languages easily.
This chapter discusses the mechanism by which you can modify the
current locale. The effects of the current locale on specific library
functions are discussed in more detail in the descriptions of those

File:, Node: Choosing Locale, Next: Locale Categories, Prev: Effects of Locale, Up: Locales
7.2 Choosing a Locale
The simplest way for the user to choose a locale is to set the
environment variable 'LANG'. This specifies a single locale to use for
all purposes. For example, a user could specify a hypothetical locale
named 'espana-castellano' to use the standard conventions of most of
The set of locales supported depends on the operating system you are
using, and so do their names. We can't make any promises about what
locales will exist, except for one standard locale called 'C' or
'POSIX'. Later we will describe how to construct locales.
A user also has the option of specifying different locales for
different purposes--in effect, choosing a mixture of multiple locales.
For example, the user might specify the locale 'espana-castellano'
for most purposes, but specify the locale 'usa-english' for currency
formatting. This might make sense if the user is a Spanish-speaking
American, working in Spanish, but representing monetary amounts in US
Note that both locales 'espana-castellano' and 'usa-english', like
all locales, would include conventions for all of the purposes to which
locales apply. However, the user can choose to use each locale for a
particular subset of those purposes.

File:, Node: Locale Categories, Next: Setting the Locale, Prev: Choosing Locale, Up: Locales
7.3 Categories of Activities that Locales Affect
The purposes that locales serve are grouped into "categories", so that a
user or a program can choose the locale for each category independently.
Here is a table of categories; each name is both an environment variable
that a user can set, and a macro name that you can use as an argument to
This category applies to collation of strings (functions 'strcoll'
and 'strxfrm'); see *note Collation Functions::.
This category applies to classification and conversion of
characters, and to multibyte and wide characters; see *note
Character Handling::, and *note Character Set Handling::.
This category applies to formatting monetary values; see *note
General Numeric::.
This category applies to formatting numeric values that are not
monetary; see *note General Numeric::.
This category applies to formatting date and time values; see *note
Formatting Calendar Time::.
This category applies to selecting the language used in the user
interface for message translation (*note The Uniforum approach::;
*note Message catalogs a la X/Open::) and contains regular
expressions for affirmative and negative responses.
This is not an environment variable; it is only a macro that you
can use with 'setlocale' to set a single locale for all purposes.
Setting this environment variable overwrites all selections by the
other 'LC_*' variables or 'LANG'.
If this environment variable is defined, its value specifies the
locale to use for all purposes except as overridden by the
variables above.
When developing the message translation functions it was felt that
the functionality provided by the variables above is not sufficient.
For example, it should be possible to specify more than one locale name.
Take a Swedish user who better speaks German than English, and a program
whose messages are output in English by default. It should be possible
to specify that the first choice of language is Swedish, the second
German, and if this also fails to use English. This is possible with
the variable 'LANGUAGE'. For further description of this GNU extension
see *note Using gettextized software::.

File:, Node: Setting the Locale, Next: Standard Locales, Prev: Locale Categories, Up: Locales
7.4 How Programs Set the Locale
A C program inherits its locale environment variables when it starts up.
This happens automatically. However, these variables do not
automatically control the locale used by the library functions, because ISO C
says that all programs start by default in the standard 'C' locale. To
use the locales specified by the environment, you must call 'setlocale'.
Call it as follows:
setlocale (LC_ALL, "");
to select a locale based on the user choice of the appropriate
environment variables.
You can also use 'setlocale' to specify a particular locale, for
general use or for a specific category.
The symbols in this section are defined in the header file
-- Function: char * setlocale (int CATEGORY, const char *LOCALE)
Preliminary: | MT-Unsafe const:locale env | AS-Unsafe init lock
heap corrupt | AC-Unsafe init corrupt lock mem fd | *Note POSIX
Safety Concepts::.
The function 'setlocale' sets the current locale for category
CATEGORY to LOCALE. A list of all the locales the system provides
can be created by running
locale -a
If CATEGORY is 'LC_ALL', this specifies the locale for all
purposes. The other possible values of CATEGORY specify an single
purpose (*note Locale Categories::).
You can also use this function to find out the current locale by
passing a null pointer as the LOCALE argument. In this case,
'setlocale' returns a string that is the name of the locale
currently selected for category CATEGORY.
The string returned by 'setlocale' can be overwritten by subsequent
calls, so you should make a copy of the string (*note Copying and
Concatenation::) if you want to save it past any further calls to
'setlocale'. (The standard library is guaranteed never to call
'setlocale' itself.)
You should not modify the string returned by 'setlocale'. It might
be the same string that was passed as an argument in a previous
call to 'setlocale'. One requirement is that the CATEGORY must be
the same in the call the string was returned and the one when the
string is passed in as LOCALE parameter.
When you read the current locale for category 'LC_ALL', the value
encodes the entire combination of selected locales for all
categories. In this case, the value is not just a single locale
name. In fact, we don't make any promises about what it looks
like. But if you specify the same "locale name" with 'LC_ALL' in a
subsequent call to 'setlocale', it restores the same combination of
locale selections.
To be sure you can use the returned string encoding the currently
selected locale at a later time, you must make a copy of the
string. It is not guaranteed that the returned pointer remains
valid over time.
When the LOCALE argument is not a null pointer, the string returned
by 'setlocale' reflects the newly-modified locale.
If you specify an empty string for LOCALE, this means to read the
appropriate environment variable and use its value to select the
locale for CATEGORY.
If a nonempty string is given for LOCALE, then the locale of that
name is used if possible.
If you specify an invalid locale name, 'setlocale' returns a null
pointer and leaves the current locale unchanged.
The path used for finding locale data can be set using the 'LOCPATH'
environment variable. The default path for finding locale data is
system specific. It is computed from the value given as the prefix
while configuring the C library. This value normally is '/usr' or '/'.
For the former the complete path is:
Here is an example showing how you might use 'setlocale' to
temporarily switch to a new locale.
#include <stddef.h>
#include <locale.h>
#include <stdlib.h>
#include <string.h>
with_other_locale (char *new_locale,
void (*subroutine) (int),
int argument)
char *old_locale, *saved_locale;
/* Get the name of the current locale. */
old_locale = setlocale (LC_ALL, NULL);
/* Copy the name so it won't be clobbered by 'setlocale'. */
saved_locale = strdup (old_locale);
if (saved_locale == NULL)
fatal ("Out of memory");
/* Now change the locale and do some stuff with it. */
setlocale (LC_ALL, new_locale);
(*subroutine) (argument);
/* Restore the original locale. */
setlocale (LC_ALL, saved_locale);
free (saved_locale);
*Portability Note:* Some ISO C systems may define additional locale
categories, and future versions of the library will do so. For
portability, assume that any symbol beginning with 'LC_' might be
defined in 'locale.h'.

File:, Node: Standard Locales, Next: Locale Information, Prev: Setting the Locale, Up: Locales
7.5 Standard Locales
The only locale names you can count on finding on all operating systems
are these three standard ones:
This is the standard C locale. The attributes and behavior it
provides are specified in the ISO C standard. When your program
starts up, it initially uses this locale by default.
This is the standard POSIX locale. Currently, it is an alias for
the standard C locale.
The empty name says to select a locale based on environment
variables. *Note Locale Categories::.
Defining and installing named locales is normally a responsibility of
the system administrator at your site (or the person who installed the
GNU C Library). It is also possible for the user to create private
locales. All this will be discussed later when describing the tool to
do so.
If your program needs to use something other than the 'C' locale, it
will be more portable if you use whatever locale the user specifies with
the environment, rather than trying to specify some non-standard locale
explicitly by name. Remember, different machines might have different
sets of locales installed.

File:, Node: Locale Information, Next: Formatting Numbers, Prev: Standard Locales, Up: Locales
7.6 Accessing Locale Information
There are several ways to access locale information. The simplest way
is to let the C library itself do the work. Several of the functions in
this library implicitly access the locale data, and use what information
is provided by the currently selected locale. This is how the locale
model is meant to work normally.
As an example take the 'strftime' function, which is meant to nicely
format date and time information (*note Formatting Calendar Time::).
Part of the standard information contained in the 'LC_TIME' category is
the names of the months. Instead of requiring the programmer to take
care of providing the translations the 'strftime' function does this all
by itself. '%A' in the format string is replaced by the appropriate
weekday name of the locale currently selected by 'LC_TIME'. This is an
easy example, and wherever possible functions do things automatically in
this way.
But there are quite often situations when there is simply no function
to perform the task, or it is simply not possible to do the work
automatically. For these cases it is necessary to access the
information in the locale directly. To do this the C library provides
two functions: 'localeconv' and 'nl_langinfo'. The former is part of ISO C
and therefore portable, but has a brain-damaged interface. The second
is part of the Unix interface and is portable in as far as the system
follows the Unix standards.
* Menu:
* The Lame Way to Locale Data:: ISO C's 'localeconv'.
* The Elegant and Fast Way:: X/Open's 'nl_langinfo'.

File:, Node: The Lame Way to Locale Data, Next: The Elegant and Fast Way, Up: Locale Information
7.6.1 'localeconv': It is portable but ...
Together with the 'setlocale' function the ISO C people invented the
'localeconv' function. It is a masterpiece of poor design. It is
expensive to use, not extendable, and not generally usable as it
provides access to only 'LC_MONETARY' and 'LC_NUMERIC' related
information. Nevertheless, if it is applicable to a given situation it
should be used since it is very portable. The function 'strfmon'
formats monetary amounts according to the selected locale using this
-- Function: struct lconv * localeconv (void)
Preliminary: | MT-Unsafe race:localeconv locale | AS-Unsafe |
AC-Safe | *Note POSIX Safety Concepts::.
The 'localeconv' function returns a pointer to a structure whose
components contain information about how numeric and monetary
values should be formatted in the current locale.
You should not modify the structure or its contents. The structure
might be overwritten by subsequent calls to 'localeconv', or by
calls to 'setlocale', but no other function in the library
overwrites this value.