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This is libc.info, 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
(Buildroot).
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
License".
(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
START-INFO-DIR-ENTRY
* Libc: (libc). C library.
END-INFO-DIR-ENTRY
INFO-DIR-SECTION GNU C library functions and macros
START-INFO-DIR-ENTRY
* 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.
* IPPORT_USERRESERVED: (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.
END-INFO-DIR-ENTRY

File: libc.info, Node: Netgroup Database, Prev: Database Example, Up: Users and Groups
29.16 Netgroup Database
=======================
* Menu:
* Netgroup Data:: Data in the Netgroup database and where
it comes from.
* Lookup Netgroup:: How to look for a particular netgroup.
* Netgroup Membership:: How to test for netgroup membership.

File: libc.info, Node: Netgroup Data, Next: Lookup Netgroup, Up: Netgroup Database
29.16.1 Netgroup Data
---------------------
Sometimes it is useful to group users according to other criteria (*note
Group Database::). E.g., it is useful to associate a certain group of
users with a certain machine. On the other hand grouping of host names
is not supported so far.
In Sun Microsystems SunOS appeared a new kind of database, the
netgroup database. It allows grouping hosts, users, and domains freely,
giving them individual names. To be more concrete, a netgroup is a list
of triples consisting of a host name, a user name, and a domain name
where any of the entries can be a wildcard entry matching all inputs. A
last possibility is that names of other netgroups can also be given in
the list specifying a netgroup. So one can construct arbitrary
hierarchies without loops.
Sun's implementation allows netgroups only for the 'nis' or 'nisplus'
service, *note Services in the NSS configuration::. The implementation
in the GNU C Library has no such restriction. An entry in either of the
input services must have the following form:
GROUPNAME ( GROUPNAME | (HOSTNAME,USERNAME,domainname) )+
Any of the fields in the triple can be empty which means anything
matches. While describing the functions we will see that the opposite
case is useful as well. I.e., there may be entries which will not match
any input. For entries like this, a name consisting of the single
character '-' shall be used.

File: libc.info, Node: Lookup Netgroup, Next: Netgroup Membership, Prev: Netgroup Data, Up: Netgroup Database
29.16.2 Looking up one Netgroup
-------------------------------
The lookup functions for netgroups are a bit different to all other
system database handling functions. Since a single netgroup can contain
many entries a two-step process is needed. First a single netgroup is
selected and then one can iterate over all entries in this netgroup.
These functions are declared in 'netdb.h'.
-- Function: int setnetgrent (const char *NETGROUP)
Preliminary: | MT-Unsafe race:netgrent locale | AS-Unsafe dlopen
plugin heap lock | AC-Unsafe corrupt lock fd mem | *Note POSIX
Safety Concepts::.
A call to this function initializes the internal state of the
library to allow following calls of the 'getnetgrent' to iterate
over all entries in the netgroup with name NETGROUP.
When the call is successful (i.e., when a netgroup with this name
exists) the return value is '1'. When the return value is '0' no
netgroup of this name is known or some other error occurred.
It is important to remember that there is only one single state for
iterating the netgroups. Even if the programmer uses the
'getnetgrent_r' function the result is not really reentrant since always
only one single netgroup at a time can be processed. If the program
needs to process more than one netgroup simultaneously she must protect
this by using external locking. This problem was introduced in the
original netgroups implementation in SunOS and since we must stay
compatible it is not possible to change this.
Some other functions also use the netgroups state. Currently these
are the 'innetgr' function and parts of the implementation of the
'compat' service part of the NSS implementation.
-- Function: int getnetgrent (char **HOSTP, char **USERP, char
**DOMAINP)
Preliminary: | MT-Unsafe race:netgrent race:netgrentbuf locale |
AS-Unsafe dlopen plugin heap lock | AC-Unsafe corrupt lock fd mem |
*Note POSIX Safety Concepts::.
This function returns the next unprocessed entry of the currently
selected netgroup. The string pointers, in which addresses are
passed in the arguments HOSTP, USERP, and DOMAINP, will contain
after a successful call pointers to appropriate strings. If the
string in the next entry is empty the pointer has the value 'NULL'.
The returned string pointers are only valid if none of the netgroup
related functions are called.
The return value is '1' if the next entry was successfully read. A
value of '0' means no further entries exist or internal errors
occurred.
-- Function: int getnetgrent_r (char **HOSTP, char **USERP, char
**DOMAINP, char *BUFFER, size_t BUFLEN)
Preliminary: | MT-Unsafe race:netgrent locale | AS-Unsafe dlopen
plugin heap lock | AC-Unsafe corrupt lock fd mem | *Note POSIX
Safety Concepts::.
This function is similar to 'getnetgrent' with only one exception:
the strings the three string pointers HOSTP, USERP, and DOMAINP
point to, are placed in the buffer of BUFLEN bytes starting at
BUFFER. This means the returned values are valid even after other
netgroup related functions are called.
The return value is '1' if the next entry was successfully read and
the buffer contains enough room to place the strings in it. '0' is
returned in case no more entries are found, the buffer is too
small, or internal errors occurred.
This function is a GNU extension. The original implementation in
the SunOS libc does not provide this function.
-- Function: void endnetgrent (void)
Preliminary: | MT-Unsafe race:netgrent | AS-Unsafe dlopen plugin
heap lock | AC-Unsafe corrupt lock fd mem | *Note POSIX Safety
Concepts::.
This function frees all buffers which were allocated to process the
last selected netgroup. As a result all string pointers returned
by calls to 'getnetgrent' are invalid afterwards.

File: libc.info, Node: Netgroup Membership, Prev: Lookup Netgroup, Up: Netgroup Database
29.16.3 Testing for Netgroup Membership
---------------------------------------
It is often not necessary to scan the whole netgroup since often the
only interesting question is whether a given entry is part of the
selected netgroup.
-- Function: int innetgr (const char *NETGROUP, const char *HOST, const
char *USER, const char *DOMAIN)
Preliminary: | MT-Unsafe race:netgrent locale | AS-Unsafe dlopen
plugin heap lock | AC-Unsafe corrupt lock fd mem | *Note POSIX
Safety Concepts::.
This function tests whether the triple specified by the parameters
HOSTP, USERP, and DOMAINP is part of the netgroup NETGROUP. Using
this function has the advantage that
1. no other netgroup function can use the global netgroup state
since internal locking is used and
2. the function is implemented more efficiently than successive
calls to the other 'set'/'get'/'endnetgrent' functions.
Any of the pointers HOSTP, USERP, and DOMAINP can be 'NULL' which
means any value is accepted in this position. This is also true
for the name '-' which should not match any other string otherwise.
The return value is '1' if an entry matching the given triple is
found in the netgroup. The return value is '0' if the netgroup
itself is not found, the netgroup does not contain the triple or
internal errors occurred.

File: libc.info, Node: System Management, Next: System Configuration, Prev: Users and Groups, Up: Top
30 System Management
********************
This chapter describes facilities for controlling the system that
underlies a process (including the operating system and hardware) and
for getting information about it. Anyone can generally use the
informational facilities, but usually only a properly privileged process
can make changes.
* Menu:
* Host Identification:: Determining the name of the machine.
* Platform Type:: Determining operating system and basic
machine type
* Filesystem Handling:: Controlling/querying mounts
* System Parameters:: Getting and setting various system parameters
To get information on parameters of the system that are built into
the system, such as the maximum length of a filename, *note System
Configuration::.

File: libc.info, Node: Host Identification, Next: Platform Type, Up: System Management
30.1 Host Identification
========================
This section explains how to identify the particular system on which
your program is running. First, let's review the various ways computer
systems are named, which is a little complicated because of the history
of the development of the Internet.
Every Unix system (also known as a host) has a host name, whether
it's connected to a network or not. In its simplest form, as used
before computer networks were an issue, it's just a word like 'chicken'.
But any system attached to the Internet or any network like it
conforms to a more rigorous naming convention as part of the Domain Name
System (DNS). In DNS, every host name is composed of two parts:
1. hostname
2. domain name
You will note that "hostname" looks a lot like "host name", but is
not the same thing, and that people often incorrectly refer to entire
host names as "domain names."
In DNS, the full host name is properly called the FQDN (Fully
Qualified Domain Name) and consists of the hostname, then a period, then
the domain name. The domain name itself usually has multiple components
separated by periods. So for example, a system's hostname may be
'chicken' and its domain name might be 'ai.mit.edu', so its FQDN (which
is its host name) is 'chicken.ai.mit.edu'.
Adding to the confusion, though, is that DNS is not the only name
space in which a computer needs to be known. Another name space is the
NIS (aka YP) name space. For NIS purposes, there is another domain
name, which is called the NIS domain name or the YP domain name. It
need not have anything to do with the DNS domain name.
Confusing things even more is the fact that in DNS, it is possible
for multiple FQDNs to refer to the same system. However, there is
always exactly one of them that is the true host name, and it is called
the canonical FQDN.
In some contexts, the host name is called a "node name."
For more information on DNS host naming, see *note Host Names::.
Prototypes for these functions appear in 'unistd.h'.
The programs 'hostname', 'hostid', and 'domainname' work by calling
these functions.
-- Function: int gethostname (char *NAME, size_t SIZE)
Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
Concepts::.
This function returns the host name of the system on which it is
called, in the array NAME. The SIZE argument specifies the size of
this array, in bytes. Note that this is _not_ the DNS hostname.
If the system participates in DNS, this is the FQDN (see above).
The return value is '0' on success and '-1' on failure. In the GNU
C Library, 'gethostname' fails if SIZE is not large enough; then
you can try again with a larger array. The following 'errno' error
condition is defined for this function:
'ENAMETOOLONG'
The SIZE argument is less than the size of the host name plus
one.
On some systems, there is a symbol for the maximum possible host
name length: 'MAXHOSTNAMELEN'. It is defined in 'sys/param.h'.
But you can't count on this to exist, so it is cleaner to handle
failure and try again.
'gethostname' stores the beginning of the host name in NAME even if
the host name won't entirely fit. For some purposes, a truncated
host name is good enough. If it is, you can ignore the error code.
-- Function: int sethostname (const char *NAME, size_t LENGTH)
Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
Concepts::.
The 'sethostname' function sets the host name of the system that
calls it to NAME, a string with length LENGTH. Only privileged
processes are permitted to do this.
Usually 'sethostname' gets called just once, at system boot time.
Often, the program that calls it sets it to the value it finds in
the file '/etc/hostname'.
Be sure to set the host name to the full host name, not just the
DNS hostname (see above).
The return value is '0' on success and '-1' on failure. The
following 'errno' error condition is defined for this function:
'EPERM'
This process cannot set the host name because it is not
privileged.
-- Function: int getdomainnname (char *NAME, size_t LENGTH)
Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
Concepts::.
'getdomainname' returns the NIS (aka YP) domain name of the system
on which it is called. Note that this is not the more popular DNS
domain name. Get that with 'gethostname'.
The specifics of this function are analogous to 'gethostname',
above.
-- Function: int setdomainname (const char *NAME, size_t LENGTH)
Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
Concepts::.
'getdomainname' sets the NIS (aka YP) domain name of the system on
which it is called. Note that this is not the more popular DNS
domain name. Set that with 'sethostname'.
The specifics of this function are analogous to 'sethostname',
above.
-- Function: long int gethostid (void)
Preliminary: | MT-Safe hostid env locale | AS-Unsafe dlopen plugin
corrupt heap lock | AC-Unsafe lock corrupt mem fd | *Note POSIX
Safety Concepts::.
This function returns the "host ID" of the machine the program is
running on. By convention, this is usually the primary Internet IP
address of that machine, converted to a 'long int'. However, on
some systems it is a meaningless but unique number which is
hard-coded for each machine.
This is not widely used. It arose in BSD 4.2, but was dropped in
BSD 4.4. It is not required by POSIX.
The proper way to query the IP address is to use 'gethostbyname' on
the results of 'gethostname'. For more information on IP
addresses, *Note Host Addresses::.
-- Function: int sethostid (long int ID)
Preliminary: | MT-Unsafe const:hostid | AS-Unsafe | AC-Unsafe
corrupt fd | *Note POSIX Safety Concepts::.
The 'sethostid' function sets the "host ID" of the host machine to
ID. Only privileged processes are permitted to do this. Usually
it happens just once, at system boot time.
The proper way to establish the primary IP address of a system is
to configure the IP address resolver to associate that IP address
with the system's host name as returned by 'gethostname'. For
example, put a record for the system in '/etc/hosts'.
See 'gethostid' above for more information on host ids.
The return value is '0' on success and '-1' on failure. The
following 'errno' error conditions are defined for this function:
'EPERM'
This process cannot set the host name because it is not
privileged.
'ENOSYS'
The operating system does not support setting the host ID. On
some systems, the host ID is a meaningless but unique number
hard-coded for each machine.

File: libc.info, Node: Platform Type, Next: Filesystem Handling, Prev: Host Identification, Up: System Management
30.2 Platform Type Identification
=================================
You can use the 'uname' function to find out some information about the
type of computer your program is running on. This function and the
associated data type are declared in the header file 'sys/utsname.h'.
As a bonus, 'uname' also gives some information identifying the
particular system your program is running on. This is the same
information which you can get with functions targeted to this purpose
described in *note Host Identification::.
-- Data Type: struct utsname
The 'utsname' structure is used to hold information returned by the
'uname' function. It has the following members:
'char sysname[]'
This is the name of the operating system in use.
'char release[]'
This is the current release level of the operating system
implementation.
'char version[]'
This is the current version level within the release of the
operating system.
'char machine[]'
This is a description of the type of hardware that is in use.
Some systems provide a mechanism to interrogate the kernel
directly for this information. On systems without such a
mechanism, the GNU C Library fills in this field based on the
configuration name that was specified when building and
installing the library.
GNU uses a three-part name to describe a system configuration;
the three parts are CPU, MANUFACTURER and SYSTEM-TYPE, and
they are separated with dashes. Any possible combination of
three names is potentially meaningful, but most such
combinations are meaningless in practice and even the
meaningful ones are not necessarily supported by any
particular GNU program.
Since the value in 'machine' is supposed to describe just the
hardware, it consists of the first two parts of the
configuration name: 'CPU-MANUFACTURER'. For example, it might
be one of these:
'"sparc-sun"', '"i386-ANYTHING"', '"m68k-hp"',
'"m68k-sony"', '"m68k-sun"', '"mips-dec"'
'char nodename[]'
This is the host name of this particular computer. In the GNU
C Library, the value is the same as that returned by
'gethostname'; see *note Host Identification::.
gethostname() is implemented with a call to uname().
'char domainname[]'
This is the NIS or YP domain name. It is the same value
returned by 'getdomainname'; see *note Host Identification::.
This element is a relatively recent invention and use of it is
not as portable as use of the rest of the structure.
-- Function: int uname (struct utsname *INFO)
Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
Concepts::.
The 'uname' function fills in the structure pointed to by INFO with
information about the operating system and host machine. A
non-negative value indicates that the data was successfully stored.
'-1' as the value indicates an error. The only error possible is
'EFAULT', which we normally don't mention as it is always a
possibility.

File: libc.info, Node: Filesystem Handling, Next: System Parameters, Prev: Platform Type, Up: System Management
30.3 Controlling and Querying Mounts
====================================
All files are in filesystems, and before you can access any file, its
filesystem must be mounted. Because of Unix's concept of _Everything is
a file_, mounting of filesystems is central to doing almost anything.
This section explains how to find out what filesystems are currently
mounted and what filesystems are available for mounting, and how to
change what is mounted.
The classic filesystem is the contents of a disk drive. The concept
is considerably more abstract, though, and lots of things other than
disk drives can be mounted.
Some block devices don't correspond to traditional devices like disk
drives. For example, a loop device is a block device whose driver uses
a regular file in another filesystem as its medium. So if that regular
file contains appropriate data for a filesystem, you can by mounting the
loop device essentially mount a regular file.
Some filesystems aren't based on a device of any kind. The "proc"
filesystem, for example, contains files whose data is made up by the
filesystem driver on the fly whenever you ask for it. And when you
write to it, the data you write causes changes in the system. No data
gets stored.
* Menu:
* Mount Information:: What is or could be mounted?
* Mount-Unmount-Remount:: Controlling what is mounted and how

File: libc.info, Node: Mount Information, Next: Mount-Unmount-Remount, Up: Filesystem Handling
30.3.1 Mount Information
------------------------
For some programs it is desirable and necessary to access information
about whether a certain filesystem is mounted and, if it is, where, or
simply to get lists of all the available filesystems. The GNU C Library
provides some functions to retrieve this information portably.
Traditionally Unix systems have a file named '/etc/fstab' which
describes all possibly mounted filesystems. The 'mount' program uses
this file to mount at startup time of the system all the necessary
filesystems. The information about all the filesystems actually mounted
is normally kept in a file named either '/var/run/mtab' or '/etc/mtab'.
Both files share the same syntax and it is crucial that this syntax is
followed all the time. Therefore it is best to never directly write the
files. The functions described in this section can do this and they
also provide the functionality to convert the external textual
representation to the internal representation.
Note that the 'fstab' and 'mtab' files are maintained on a system by
_convention_. It is possible for the files not to exist or not to be
consistent with what is really mounted or available to mount, if the
system's administration policy allows it. But programs that mount and
unmount filesystems typically maintain and use these files as described
herein.
The filenames given above should never be used directly. The
portable way to handle these file is to use the macro '_PATH_FSTAB',
defined in 'fstab.h', or '_PATH_MNTTAB', defined in 'mntent.h' and
'paths.h', for 'fstab'; and the macro '_PATH_MOUNTED', also defined in
'mntent.h' and 'paths.h', for 'mtab'. There are also two alternate
macro names 'FSTAB', 'MNTTAB', and 'MOUNTED' defined but these names are
deprecated and kept only for backward compatibility. The names
'_PATH_MNTTAB' and '_PATH_MOUNTED' should always be used.
* Menu:
* fstab:: The 'fstab' file
* mtab:: The 'mtab' file
* Other Mount Information:: Other (non-libc) sources of mount information

File: libc.info, Node: fstab, Next: mtab, Up: Mount Information
30.3.1.1 The 'fstab' file
.........................
The internal representation for entries of the file is 'struct fstab',
defined in 'fstab.h'.
-- Data Type: struct fstab
This structure is used with the 'getfsent', 'getfsspec', and
'getfsfile' functions.
'char *fs_spec'
This element describes the device from which the filesystem is
mounted. Normally this is the name of a special device, such
as a hard disk partition, but it could also be a more or less
generic string. For "NFS" it would be a hostname and
directory name combination.
Even though the element is not declared 'const' it shouldn't
be modified. The missing 'const' has historic reasons, since
this function predates ISO C. The same is true for the other
string elements of this structure.
'char *fs_file'
This describes the mount point on the local system. I.e.,
accessing any file in this filesystem has implicitly or
explicitly this string as a prefix.
'char *fs_vfstype'
This is the type of the filesystem. Depending on what the
underlying kernel understands it can be any string.
'char *fs_mntops'
This is a string containing options passed to the kernel with
the 'mount' call. Again, this can be almost anything. There
can be more than one option, separated from the others by a
comma. Each option consists of a name and an optional value
part, introduced by an '=' character.
If the value of this element must be processed it should
ideally be done using the 'getsubopt' function; see *note
Suboptions::.
'const char *fs_type'
This name is poorly chosen. This element points to a string
(possibly in the 'fs_mntops' string) which describes the modes
with which the filesystem is mounted. 'fstab' defines five
macros to describe the possible values:
'FSTAB_RW'
The filesystems gets mounted with read and write enabled.
'FSTAB_RQ'
The filesystems gets mounted with read and write enabled.
Write access is restricted by quotas.
'FSTAB_RO'
The filesystem gets mounted read-only.
'FSTAB_SW'
This is not a real filesystem, it is a swap device.
'FSTAB_XX'
This entry from the 'fstab' file is totally ignored.
Testing for equality with these value must happen using
'strcmp' since these are all strings. Comparing the pointer
will probably always fail.
'int fs_freq'
This element describes the dump frequency in days.
'int fs_passno'
This element describes the pass number on parallel dumps. It
is closely related to the 'dump' utility used on Unix systems.
To read the entire content of the of the 'fstab' file the GNU C
Library contains a set of three functions which are designed in the
usual way.
-- Function: int setfsent (void)
Preliminary: | MT-Unsafe race:fsent | AS-Unsafe heap corrupt lock |
AC-Unsafe corrupt lock mem fd | *Note POSIX Safety Concepts::.
This function makes sure that the internal read pointer for the
'fstab' file is at the beginning of the file. This is done by
either opening the file or resetting the read pointer.
Since the file handle is internal to the libc this function is not
thread-safe.
This function returns a non-zero value if the operation was
successful and the 'getfs*' functions can be used to read the
entries of the file.
-- Function: void endfsent (void)
Preliminary: | MT-Unsafe race:fsent | AS-Unsafe heap corrupt lock |
AC-Unsafe corrupt lock mem fd | *Note POSIX Safety Concepts::.
This function makes sure that all resources acquired by a prior
call to 'setfsent' (explicitly or implicitly by calling 'getfsent')
are freed.
-- Function: struct fstab * getfsent (void)
Preliminary: | MT-Unsafe race:fsent locale | AS-Unsafe corrupt heap
lock | AC-Unsafe corrupt lock mem | *Note POSIX Safety Concepts::.
This function returns the next entry of the 'fstab' file. If this
is the first call to any of the functions handling 'fstab' since
program start or the last call of 'endfsent', the file will be
opened.
The function returns a pointer to a variable of type 'struct
fstab'. This variable is shared by all threads and therefore this
function is not thread-safe. If an error occurred 'getfsent'
returns a 'NULL' pointer.
-- Function: struct fstab * getfsspec (const char *NAME)
Preliminary: | MT-Unsafe race:fsent locale | AS-Unsafe corrupt heap
lock | AC-Unsafe corrupt lock mem | *Note POSIX Safety Concepts::.
This function returns the next entry of the 'fstab' file which has
a string equal to NAME pointed to by the 'fs_spec' element. Since
there is normally exactly one entry for each special device it
makes no sense to call this function more than once for the same
argument. If this is the first call to any of the functions
handling 'fstab' since program start or the last call of
'endfsent', the file will be opened.
The function returns a pointer to a variable of type 'struct
fstab'. This variable is shared by all threads and therefore this
function is not thread-safe. If an error occurred 'getfsent'
returns a 'NULL' pointer.
-- Function: struct fstab * getfsfile (const char *NAME)
Preliminary: | MT-Unsafe race:fsent locale | AS-Unsafe corrupt heap
lock | AC-Unsafe corrupt lock mem | *Note POSIX Safety Concepts::.
This function returns the next entry of the 'fstab' file which has
a string equal to NAME pointed to by the 'fs_file' element. Since
there is normally exactly one entry for each mount point it makes
no sense to call this function more than once for the same
argument. If this is the first call to any of the functions
handling 'fstab' since program start or the last call of
'endfsent', the file will be opened.
The function returns a pointer to a variable of type 'struct
fstab'. This variable is shared by all threads and therefore this
function is not thread-safe. If an error occurred 'getfsent'
returns a 'NULL' pointer.

File: libc.info, Node: mtab, Next: Other Mount Information, Prev: fstab, Up: Mount Information
30.3.1.2 The 'mtab' file
........................
The following functions and data structure access the 'mtab' file.
-- Data Type: struct mntent
This structure is used with the 'getmntent', 'getmntent_t',
'addmntent', and 'hasmntopt' functions.
'char *mnt_fsname'
This element contains a pointer to a string describing the
name of the special device from which the filesystem is
mounted. It corresponds to the 'fs_spec' element in 'struct
fstab'.
'char *mnt_dir'
This element points to a string describing the mount point of
the filesystem. It corresponds to the 'fs_file' element in
'struct fstab'.
'char *mnt_type'
'mnt_type' describes the filesystem type and is therefore
equivalent to 'fs_vfstype' in 'struct fstab'. 'mntent.h'
defines a few symbolic names for some of the values this
string can have. But since the kernel can support arbitrary
filesystems it does not make much sense to give them symbolic
names. If one knows the symbol name one also knows the
filesystem name. Nevertheless here follows the list of the
symbols provided in 'mntent.h'.
'MNTTYPE_IGNORE'
This symbol expands to '"ignore"'. The value is sometime
used in 'fstab' files to make sure entries are not used
without removing them.
'MNTTYPE_NFS'
Expands to '"nfs"'. Using this macro sometimes could
make sense since it names the default NFS implementation,
in case both version 2 and 3 are supported.
'MNTTYPE_SWAP'
This symbol expands to '"swap"'. It names the special
'fstab' entry which names one of the possibly multiple
swap partitions.
'char *mnt_opts'
The element contains a string describing the options used
while mounting the filesystem. As for the equivalent element
'fs_mntops' of 'struct fstab' it is best to use the function
'getsubopt' (*note Suboptions::) to access the parts of this
string.
The 'mntent.h' file defines a number of macros with string
values which correspond to some of the options understood by
the kernel. There might be many more options which are
possible so it doesn't make much sense to rely on these macros
but to be consistent here is the list:
'MNTOPT_DEFAULTS'
Expands to '"defaults"'. This option should be used
alone since it indicates all values for the customizable
values are chosen to be the default.
'MNTOPT_RO'
Expands to '"ro"'. See the 'FSTAB_RO' value, it means
the filesystem is mounted read-only.
'MNTOPT_RW'
Expand to '"rw"'. See the 'FSTAB_RW' value, it means the
filesystem is mounted with read and write permissions.
'MNTOPT_SUID'
Expands to '"suid"'. This means that the SUID bit (*note
How Change Persona::) is respected when a program from
the filesystem is started.
'MNTOPT_NOSUID'
Expands to '"nosuid"'. This is the opposite of
'MNTOPT_SUID', the SUID bit for all files from the
filesystem is ignored.
'MNTOPT_NOAUTO'
Expands to '"noauto"'. At startup time the 'mount'
program will ignore this entry if it is started with the
'-a' option to mount all filesystems mentioned in the
'fstab' file.
As for the 'FSTAB_*' entries introduced above it is important
to use 'strcmp' to check for equality.
'mnt_freq'
This elements corresponds to 'fs_freq' and also specifies the
frequency in days in which dumps are made.
'mnt_passno'
This element is equivalent to 'fs_passno' with the same
meaning which is uninteresting for all programs beside 'dump'.
For accessing the 'mtab' file there is again a set of three functions
to access all entries in a row. Unlike the functions to handle 'fstab'
these functions do not access a fixed file and there is even a thread
safe variant of the get function. Beside this the GNU C Library
contains functions to alter the file and test for specific options.
-- Function: FILE * setmntent (const char *FILE, const char *MODE)
Preliminary: | MT-Safe | AS-Unsafe heap lock | AC-Unsafe mem fd
lock | *Note POSIX Safety Concepts::.
The 'setmntent' function prepares the file named FILE which must be
in the format of a 'fstab' and 'mtab' file for the upcoming
processing through the other functions of the family. The MODE
parameter can be chosen in the way the OPENTYPE parameter for
'fopen' (*note Opening Streams::) can be chosen. If the file is
opened for writing the file is also allowed to be empty.
If the file was successfully opened 'setmntent' returns a file
descriptor for future use. Otherwise the return value is 'NULL'
and 'errno' is set accordingly.
-- Function: int endmntent (FILE *STREAM)
Preliminary: | MT-Safe | AS-Unsafe heap lock | AC-Unsafe lock mem
fd | *Note POSIX Safety Concepts::.
This function takes for the STREAM parameter a file handle which
previously was returned from the 'setmntent' call. 'endmntent'
closes the stream and frees all resources.
The return value is 1 unless an error occurred in which case it is
0.
-- Function: struct mntent * getmntent (FILE *STREAM)
Preliminary: | MT-Unsafe race:mntentbuf locale | AS-Unsafe corrupt
heap init | AC-Unsafe init corrupt lock mem | *Note POSIX Safety
Concepts::.
The 'getmntent' function takes as the parameter a file handle
previously returned by successful call to 'setmntent'. It returns
a pointer to a static variable of type 'struct mntent' which is
filled with the information from the next entry from the file
currently read.
The file format used prescribes the use of spaces or tab characters
to separate the fields. This makes it harder to use name
containing one of these characters (e.g., mount points using
spaces). Therefore these characters are encoded in the files and
the 'getmntent' function takes care of the decoding while reading
the entries back in. ''\040'' is used to encode a space character,
''\011'' to encode a tab character, ''\012'' to encode a newline
character, and ''\\'' to encode a backslash.
If there was an error or the end of the file is reached the return
value is 'NULL'.
This function is not thread-safe since all calls to this function
return a pointer to the same static variable. 'getmntent_r' should
be used in situations where multiple threads access the file.
-- Function: struct mntent * getmntent_r (FILE *STREAM, struct mntent
*RESULT, char *BUFFER, int BUFSIZE)
Preliminary: | MT-Safe locale | AS-Unsafe corrupt heap | AC-Unsafe
corrupt lock mem | *Note POSIX Safety Concepts::.
The 'getmntent_r' function is the reentrant variant of 'getmntent'.
It also returns the next entry from the file and returns a pointer.
The actual variable the values are stored in is not static, though.
Instead the function stores the values in the variable pointed to
by the RESULT parameter. Additional information (e.g., the strings
pointed to by the elements of the result) are kept in the buffer of
size BUFSIZE pointed to by BUFFER.
Escaped characters (space, tab, backslash) are converted back in
the same way as it happens for 'getmentent'.
The function returns a 'NULL' pointer in error cases. Errors could
be:
* error while reading the file,
* end of file reached,
* BUFSIZE is too small for reading a complete new entry.
-- Function: int addmntent (FILE *STREAM, const struct mntent *MNT)
Preliminary: | MT-Unsafe race:stream locale | AS-Unsafe corrupt |
AC-Unsafe corrupt | *Note POSIX Safety Concepts::.
The 'addmntent' function allows adding a new entry to the file
previously opened with 'setmntent'. The new entries are always
appended. I.e., even if the position of the file descriptor is not
at the end of the file this function does not overwrite an existing
entry following the current position.
The implication of this is that to remove an entry from a file one
has to create a new file while leaving out the entry to be removed
and after closing the file remove the old one and rename the new
file to the chosen name.
This function takes care of spaces and tab characters in the names
to be written to the file. It converts them and the backslash
character into the format describe in the 'getmntent' description
above.
This function returns 0 in case the operation was successful.
Otherwise the return value is 1 and 'errno' is set appropriately.
-- Function: char * hasmntopt (const struct mntent *MNT, const char
*OPT)
Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
Concepts::.
This function can be used to check whether the string pointed to by
the 'mnt_opts' element of the variable pointed to by MNT contains
the option OPT. If this is true a pointer to the beginning of the
option in the 'mnt_opts' element is returned. If no such option
exists the function returns 'NULL'.
This function is useful to test whether a specific option is
present but when all options have to be processed one is better off
with using the 'getsubopt' function to iterate over all options in
the string.

File: libc.info, Node: Other Mount Information, Prev: mtab, Up: Mount Information
30.3.1.3 Other (Non-libc) Sources of Mount Information
......................................................
On a system with a Linux kernel and the 'proc' filesystem, you can get
information on currently mounted filesystems from the file 'mounts' in
the 'proc' filesystem. Its format is similar to that of the 'mtab'
file, but represents what is truly mounted without relying on facilities
outside the kernel to keep 'mtab' up to date.

File: libc.info, Node: Mount-Unmount-Remount, Prev: Mount Information, Up: Filesystem Handling
30.3.2 Mount, Unmount, Remount
------------------------------
This section describes the functions for mounting, unmounting, and
remounting filesystems.
Only the superuser can mount, unmount, or remount a filesystem.
These functions do not access the 'fstab' and 'mtab' files. You
should maintain and use these separately. *Note Mount Information::.
The symbols in this section are declared in 'sys/mount.h'.
-- Function: int mount (const char *SPECIAL_FILE, const char *DIR,
const char *FSTYPE, unsigned long int OPTIONS, const void
*DATA)
Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
Concepts::.
'mount' mounts or remounts a filesystem. The two operations are
quite different and are merged rather unnaturally into this one
function. The 'MS_REMOUNT' option, explained below, determines
whether 'mount' mounts or remounts.
For a mount, the filesystem on the block device represented by the
device special file named SPECIAL_FILE gets mounted over the mount
point DIR. This means that the directory DIR (along with any files
in it) is no longer visible; in its place (and still with the name
DIR) is the root directory of the filesystem on the device.
As an exception, if the filesystem type (see below) is one which is
not based on a device (e.g. "proc"), 'mount' instantiates a
filesystem and mounts it over DIR and ignores SPECIAL_FILE.
For a remount, DIR specifies the mount point where the filesystem
to be remounted is (and remains) mounted and SPECIAL_FILE is
ignored. Remounting a filesystem means changing the options that
control operations on the filesystem while it is mounted. It does
not mean unmounting and mounting again.
For a mount, you must identify the type of the filesystem as
FSTYPE. This type tells the kernel how to access the filesystem
and can be thought of as the name of a filesystem driver. The
acceptable values are system dependent. On a system with a Linux
kernel and the 'proc' filesystem, the list of possible values is in
the file 'filesystems' in the 'proc' filesystem (e.g. type 'cat
/proc/filesystems' to see the list). With a Linux kernel, the
types of filesystems that 'mount' can mount, and their type names,
depends on what filesystem drivers are configured into the kernel
or loaded as loadable kernel modules. An example of a common value
for FSTYPE is 'ext2'.
For a remount, 'mount' ignores FSTYPE.
OPTIONS specifies a variety of options that apply until the
filesystem is unmounted or remounted. The precise meaning of an
option depends on the filesystem and with some filesystems, an
option may have no effect at all. Furthermore, for some
filesystems, some of these options (but never 'MS_RDONLY') can be
overridden for individual file accesses via 'ioctl'.
OPTIONS is a bit string with bit fields defined using the following
mask and masked value macros:
'MS_MGC_MASK'
This multibit field contains a magic number. If it does not
have the value 'MS_MGC_VAL', 'mount' assumes all the following
bits are zero and the DATA argument is a null string,
regardless of their actual values.
'MS_REMOUNT'
This bit on means to remount the filesystem. Off means to
mount it.
'MS_RDONLY'
This bit on specifies that no writing to the filesystem shall
be allowed while it is mounted. This cannot be overridden by
'ioctl'. This option is available on nearly all filesystems.
'S_IMMUTABLE'
This bit on specifies that no writing to the files in the
filesystem shall be allowed while it is mounted. This can be
overridden for a particular file access by a properly
privileged call to 'ioctl'. This option is a relatively new
invention and is not available on many filesystems.
'S_APPEND'
This bit on specifies that the only file writing that shall be
allowed while the filesystem is mounted is appending. Some
filesystems allow this to be overridden for a particular
process by a properly privileged call to 'ioctl'. This is a
relatively new invention and is not available on many
filesystems.
'MS_NOSUID'
This bit on specifies that Setuid and Setgid permissions on
files in the filesystem shall be ignored while it is mounted.
'MS_NOEXEC'
This bit on specifies that no files in the filesystem shall be
executed while the filesystem is mounted.
'MS_NODEV'
This bit on specifies that no device special files in the
filesystem shall be accessible while the filesystem is
mounted.
'MS_SYNCHRONOUS'
This bit on specifies that all writes to the filesystem while
it is mounted shall be synchronous; i.e., data shall be synced
before each write completes rather than held in the buffer
cache.
'MS_MANDLOCK'
This bit on specifies that mandatory locks on files shall be
permitted while the filesystem is mounted.
'MS_NOATIME'
This bit on specifies that access times of files shall not be
updated when the files are accessed while the filesystem is
mounted.
'MS_NODIRATIME'
This bit on specifies that access times of directories shall
not be updated when the directories are accessed while the
filesystem in mounted.
Any bits not covered by the above masks should be set off;
otherwise, results are undefined.
The meaning of DATA depends on the filesystem type and is
controlled entirely by the filesystem driver in the kernel.
Example:
#include <sys/mount.h>
mount("/dev/hdb", "/cdrom", MS_MGC_VAL | MS_RDONLY | MS_NOSUID, "");
mount("/dev/hda2", "/mnt", MS_MGC_VAL | MS_REMOUNT, "");
Appropriate arguments for 'mount' are conventionally recorded in
the 'fstab' table. *Note Mount Information::.
The return value is zero if the mount or remount is successful.
Otherwise, it is '-1' and 'errno' is set appropriately. The values
of 'errno' are filesystem dependent, but here is a general list:
'EPERM'
The process is not superuser.
'ENODEV'
The file system type FSTYPE is not known to the kernel.
'ENOTBLK'
The file DEV is not a block device special file.
'EBUSY'
* The device is already mounted.
* The mount point is busy. (E.g. it is some process'
working directory or has a filesystem mounted on it
already).
* The request is to remount read-only, but there are files
open for write.
'EINVAL'
* A remount was attempted, but there is no filesystem
mounted over the specified mount point.
* The supposed filesystem has an invalid superblock.
'EACCES'
* The filesystem is inherently read-only (possibly due to a
switch on the device) and the process attempted to mount
it read/write (by setting the 'MS_RDONLY' bit off).
* SPECIAL_FILE or DIR is not accessible due to file
permissions.
* SPECIAL_FILE is not accessible because it is in a
filesystem that is mounted with the 'MS_NODEV' option.
'EM_FILE'
The table of dummy devices is full. 'mount' needs to create a
dummy device (aka "unnamed" device) if the filesystem being
mounted is not one that uses a device.
-- Function: int umount2 (const char *FILE, int FLAGS)
Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
Concepts::.
'umount2' unmounts a filesystem.
You can identify the filesystem to unmount either by the device
special file that contains the filesystem or by the mount point.
The effect is the same. Specify either as the string FILE.
FLAGS contains the one-bit field identified by the following mask
macro:
'MNT_FORCE'
This bit on means to force the unmounting even if the
filesystem is busy, by making it unbusy first. If the bit is
off and the filesystem is busy, 'umount2' fails with 'errno' =
'EBUSY'. Depending on the filesystem, this may override all,
some, or no busy conditions.
All other bits in FLAGS should be set to zero; otherwise, the
result is undefined.
Example:
#include <sys/mount.h>
umount2("/mnt", MNT_FORCE);
umount2("/dev/hdd1", 0);
After the filesystem is unmounted, the directory that was the mount
point is visible, as are any files in it.
As part of unmounting, 'umount2' syncs the filesystem.
If the unmounting is successful, the return value is zero.
Otherwise, it is '-1' and 'errno' is set accordingly:
'EPERM'
The process is not superuser.
'EBUSY'
The filesystem cannot be unmounted because it is busy. E.g.
it contains a directory that is some process's working
directory or a file that some process has open. With some
filesystems in some cases, you can avoid this failure with the
'MNT_FORCE' option.
'EINVAL'
FILE validly refers to a file, but that file is neither a
mount point nor a device special file of a currently mounted
filesystem.
This function is not available on all systems.
-- Function: int umount (const char *FILE)
Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
Concepts::.
'umount' does the same thing as 'umount2' with FLAGS set to zeroes.
It is more widely available than 'umount2' but since it lacks the
possibility to forcefully unmount a filesystem is deprecated when
'umount2' is also available.

File: libc.info, Node: System Parameters, Prev: Filesystem Handling, Up: System Management
30.4 System Parameters
======================
This section describes the 'sysctl' function, which gets and sets a
variety of system parameters.
The symbols used in this section are declared in the file
'sys/sysctl.h'.
-- Function: int sysctl (int *NAMES, int NLEN, void *OLDVAL, size_t
*OLDLENP, void *NEWVAL, size_t NEWLEN)
Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
Concepts::.
'sysctl' gets or sets a specified system parameter. There are so
many of these parameters that it is not practical to list them all
here, but here are some examples:
* network domain name
* paging parameters
* network Address Resolution Protocol timeout time
* maximum number of files that may be open
* root filesystem device
* when kernel was built
The set of available parameters depends on the kernel configuration
and can change while the system is running, particularly when you
load and unload loadable kernel modules.
The system parameters with which 'syslog' is concerned are arranged
in a hierarchical structure like a hierarchical filesystem. To
identify a particular parameter, you specify a path through the
structure in a way analogous to specifying the pathname of a file.
Each component of the path is specified by an integer and each of
these integers has a macro defined for it by 'sys/sysctl.h'. NAMES
is the path, in the form of an array of integers. Each component
of the path is one element of the array, in order. NLEN is the
number of components in the path.
For example, the first component of the path for all the paging
parameters is the value 'CTL_VM'. For the free page thresholds,
the second component of the path is 'VM_FREEPG'. So to get the
free page threshold values, make NAMES an array containing the two
elements 'CTL_VM' and 'VM_FREEPG' and make NLEN = 2.
The format of the value of a parameter depends on the parameter.
Sometimes it is an integer; sometimes it is an ASCII string;
sometimes it is an elaborate structure. In the case of the free
page thresholds used in the example above, the parameter value is a
structure containing several integers.
In any case, you identify a place to return the parameter's value
with OLDVAL and specify the amount of storage available at that
location as *OLDLENP. *OLDLENP does double duty because it is also
the output location that contains the actual length of the returned
value.
If you don't want the parameter value returned, specify a null
pointer for OLDVAL.
To set the parameter, specify the address and length of the new
value as NEWVAL and NEWLEN. If you don't want to set the
parameter, specify a null pointer as NEWVAL.
If you get and set a parameter in the same 'sysctl' call, the value
returned is the value of the parameter before it was set.
Each system parameter has a set of permissions similar to the
permissions for a file (including the permissions on directories in
its path) that determine whether you may get or set it. For the
purposes of these permissions, every parameter is considered to be
owned by the superuser and Group 0 so processes with that effective
uid or gid may have more access to system parameters. Unlike with
files, the superuser does not invariably have full permission to
all system parameters, because some of them are designed not to be
changed ever.
'sysctl' returns a zero return value if it succeeds. Otherwise, it
returns '-1' and sets 'errno' appropriately. Besides the failures
that apply to all system calls, the following are the 'errno' codes
for all possible failures:
'EPERM'
The process is not permitted to access one of the components
of the path of the system parameter or is not permitted to
access the system parameter itself in the way (read or write)
that it requested.
'ENOTDIR'
There is no system parameter corresponding to NAME.
'EFAULT'
OLDVAL is not null, which means the process wanted to read the
parameter, but *OLDLENP is zero, so there is no place to
return it.
'EINVAL'
* The process attempted to set a system parameter to a
value that is not valid for that parameter.
* The space provided for the return of the system parameter
is not the right size for that parameter.
'ENOMEM'
This value may be returned instead of the more correct
'EINVAL' in some cases where the space provided for the return
of the system parameter is too small.
If you have a Linux kernel with the 'proc' filesystem, you can get
and set most of the same parameters by reading and writing to files in
the 'sys' directory of the 'proc' filesystem. In the 'sys' directory,
the directory structure represents the hierarchical structure of the
parameters. E.g. you can display the free page thresholds with
cat /proc/sys/vm/freepages
Some more traditional and more widely available, though less general,
GNU C Library functions for getting and setting some of the same system
parameters are:
* 'getdomainname', 'setdomainname'
* 'gethostname', 'sethostname' (*Note Host Identification::.)
* 'uname' (*Note Platform Type::.)
* 'bdflush'

File: libc.info, Node: System Configuration, Next: Cryptographic Functions, Prev: System Management, Up: Top
31 System Configuration Parameters
**********************************
The functions and macros listed in this chapter give information about
configuration parameters of the operating system--for example, capacity
limits, presence of optional POSIX features, and the default path for
executable files (*note String Parameters::).
* Menu:
* General Limits:: Constants and functions that describe
various process-related limits that have
one uniform value for any given machine.
* System Options:: Optional POSIX features.
* Version Supported:: Version numbers of POSIX.1 and POSIX.2.
* Sysconf:: Getting specific configuration values
of general limits and system options.
* Minimums:: Minimum values for general limits.
* Limits for Files:: Size limitations that pertain to individual files.
These can vary between file systems
or even from file to file.
* Options for Files:: Optional features that some files may support.
* File Minimums:: Minimum values for file limits.
* Pathconf:: Getting the limit values for a particular file.
* Utility Limits:: Capacity limits of some POSIX.2 utility programs.
* Utility Minimums:: Minimum allowable values of those limits.
* String Parameters:: Getting the default search path.

File: libc.info, Node: General Limits, Next: System Options, Up: System Configuration
31.1 General Capacity Limits
============================
The POSIX.1 and POSIX.2 standards specify a number of parameters that
describe capacity limitations of the system. These limits can be fixed
constants for a given operating system, or they can vary from machine to
machine. For example, some limit values may be configurable by the
system administrator, either at run time or by rebuilding the kernel,
and this should not require recompiling application programs.
Each of the following limit parameters has a macro that is defined in
'limits.h' only if the system has a fixed, uniform limit for the
parameter in question. If the system allows different file systems or
files to have different limits, then the macro is undefined; use
'sysconf' to find out the limit that applies at a particular time on a
particular machine. *Note Sysconf::.
Each of these parameters also has another macro, with a name starting
with '_POSIX', which gives the lowest value that the limit is allowed to
have on _any_ POSIX system. *Note Minimums::.
-- Macro: int ARG_MAX
If defined, the unvarying maximum combined length of the ARGV and
ENVIRON arguments that can be passed to the 'exec' functions.
-- Macro: int CHILD_MAX
If defined, the unvarying maximum number of processes that can
exist with the same real user ID at any one time. In BSD and GNU,
this is controlled by the 'RLIMIT_NPROC' resource limit; *note
Limits on Resources::.
-- Macro: int OPEN_MAX
If defined, the unvarying maximum number of files that a single
process can have open simultaneously. In BSD and GNU, this is
controlled by the 'RLIMIT_NOFILE' resource limit; *note Limits on
Resources::.
-- Macro: int STREAM_MAX
If defined, the unvarying maximum number of streams that a single
process can have open simultaneously. *Note Opening Streams::.
-- Macro: int TZNAME_MAX
If defined, the unvarying maximum length of a time zone name.
*Note Time Zone Functions::.
These limit macros are always defined in 'limits.h'.
-- Macro: int NGROUPS_MAX
The maximum number of supplementary group IDs that one process can
have.
The value of this macro is actually a lower bound for the maximum.
That is, you can count on being able to have that many
supplementary group IDs, but a particular machine might let you
have even more. You can use 'sysconf' to see whether a particular
machine will let you have more (*note Sysconf::).
-- Macro: ssize_t SSIZE_MAX
The largest value that can fit in an object of type 'ssize_t'.
Effectively, this is the limit on the number of bytes that can be
read or written in a single operation.
This macro is defined in all POSIX systems because this limit is
never configurable.
-- Macro: int RE_DUP_MAX
The largest number of repetitions you are guaranteed is allowed in
the construct '\{MIN,MAX\}' in a regular expression.
The value of this macro is actually a lower bound for the maximum.
That is, you can count on being able to have that many repetitions,
but a particular machine might let you have even more. You can use
'sysconf' to see whether a particular machine will let you have
more (*note Sysconf::). And even the value that 'sysconf' tells
you is just a lower bound--larger values might work.
This macro is defined in all POSIX.2 systems, because POSIX.2 says
it should always be defined even if there is no specific imposed
limit.

File: libc.info, Node: System Options, Next: Version Supported, Prev: General Limits, Up: System Configuration
31.2 Overall System Options
===========================
POSIX defines certain system-specific options that not all POSIX systems
support. Since these options are provided in the kernel, not in the
library, simply using the GNU C Library does not guarantee any of these
features is supported; it depends on the system you are using.
You can test for the availability of a given option using the macros
in this section, together with the function 'sysconf'. The macros are
defined only if you include 'unistd.h'.
For the following macros, if the macro is defined in 'unistd.h', then
the option is supported. Otherwise, the option may or may not be
supported; use 'sysconf' to find out. *Note Sysconf::.
-- Macro: int _POSIX_JOB_CONTROL
If this symbol is defined, it indicates that the system supports
job control. Otherwise, the implementation behaves as if all
processes within a session belong to a single process group. *Note
Job Control::.
-- Macro: int _POSIX_SAVED_IDS
If this symbol is defined, it indicates that the system remembers
the effective user and group IDs of a process before it executes an
executable file with the set-user-ID or set-group-ID bits set, and
that explicitly changing the effective user or group IDs back to
these values is permitted. If this option is not defined, then if
a nonprivileged process changes its effective user or group ID to
the real user or group ID of the process, it can't change it back
again. *Note Enable/Disable Setuid::.
For the following macros, if the macro is defined in 'unistd.h', then
its value indicates whether the option is supported. A value of '-1'
means no, and any other value means yes. If the macro is not defined,
then the option may or may not be supported; use 'sysconf' to find out.
*Note Sysconf::.
-- Macro: int _POSIX2_C_DEV
If this symbol is defined, it indicates that the system has the
POSIX.2 C compiler command, 'c89'. The GNU C Library always
defines this as '1', on the assumption that you would not have
installed it if you didn't have a C compiler.
-- Macro: int _POSIX2_FORT_DEV
If this symbol is defined, it indicates that the system has the
POSIX.2 Fortran compiler command, 'fort77'. The GNU C Library
never defines this, because we don't know what the system has.
-- Macro: int _POSIX2_FORT_RUN
If this symbol is defined, it indicates that the system has the
POSIX.2 'asa' command to interpret Fortran carriage control. The
GNU C Library never defines this, because we don't know what the
system has.
-- Macro: int _POSIX2_LOCALEDEF
If this symbol is defined, it indicates that the system has the
POSIX.2 'localedef' command. The GNU C Library never defines this,
because we don't know what the system has.
-- Macro: int _POSIX2_SW_DEV
If this symbol is defined, it indicates that the system has the
POSIX.2 commands 'ar', 'make', and 'strip'. The GNU C Library
always defines this as '1', on the assumption that you had to have
'ar' and 'make' to install the library, and it's unlikely that
'strip' would be absent when those are present.

File: libc.info, Node: Version Supported, Next: Sysconf, Prev: System Options, Up: System Configuration
31.3 Which Version of POSIX is Supported
========================================
-- Macro: long int _POSIX_VERSION
This constant represents the version of the POSIX.1 standard to
which the implementation conforms. For an implementation
conforming to the 1995 POSIX.1 standard, the value is the integer
'199506L'.
'_POSIX_VERSION' is always defined (in 'unistd.h') in any POSIX
system.
*Usage Note:* Don't try to test whether the system supports POSIX
by including 'unistd.h' and then checking whether '_POSIX_VERSION'
is defined. On a non-POSIX system, this will probably fail because
there is no 'unistd.h'. We do not know of _any_ way you can
reliably test at compilation time whether your target system
supports POSIX or whether 'unistd.h' exists.
-- Macro: long int _POSIX2_C_VERSION
This constant represents the version of the POSIX.2 standard which
the library and system kernel support. We don't know what value
this will be for the first version of the POSIX.2 standard, because
the value is based on the year and month in which the standard is
officially adopted.
The value of this symbol says nothing about the utilities installed
on the system.
*Usage Note:* You can use this macro to tell whether a POSIX.1
system library supports POSIX.2 as well. Any POSIX.1 system
contains 'unistd.h', so include that file and then test 'defined
(_POSIX2_C_VERSION)'.

File: libc.info, Node: Sysconf, Next: Minimums, Prev: Version Supported, Up: System Configuration
31.4 Using 'sysconf'
====================
When your system has configurable system limits, you can use the
'sysconf' function to find out the value that applies to any particular
machine. The function and the associated PARAMETER constants are
declared in the header file 'unistd.h'.
* Menu:
* Sysconf Definition:: Detailed specifications of 'sysconf'.
* Constants for Sysconf:: The list of parameters 'sysconf' can read.
* Examples of Sysconf:: How to use 'sysconf' and the parameter
macros properly together.

File: libc.info, Node: Sysconf Definition, Next: Constants for Sysconf, Up: Sysconf
31.4.1 Definition of 'sysconf'
------------------------------
-- Function: long int sysconf (int PARAMETER)
Preliminary: | MT-Safe env | AS-Unsafe lock heap | AC-Unsafe lock
mem fd | *Note POSIX Safety Concepts::.
This function is used to inquire about runtime system parameters.
The PARAMETER argument should be one of the '_SC_' symbols listed
below.
The normal return value from 'sysconf' is the value you requested.
A value of '-1' is returned both if the implementation does not
impose a limit, and in case of an error.
The following 'errno' error conditions are defined for this
function:
'EINVAL'
The value of the PARAMETER is invalid.

File: libc.info, Node: Constants for Sysconf, Next: Examples of Sysconf, Prev: Sysconf Definition, Up: Sysconf
31.4.2 Constants for 'sysconf' Parameters
-----------------------------------------
Here are the symbolic constants for use as the PARAMETER argument to
'sysconf'. The values are all integer constants (more specifically,
enumeration type values).
'_SC_ARG_MAX'
Inquire about the parameter corresponding to 'ARG_MAX'.
'_SC_CHILD_MAX'
Inquire about the parameter corresponding to 'CHILD_MAX'.
'_SC_OPEN_MAX'
Inquire about the parameter corresponding to 'OPEN_MAX'.
'_SC_STREAM_MAX'
Inquire about the parameter corresponding to 'STREAM_MAX'.
'_SC_TZNAME_MAX'
Inquire about the parameter corresponding to 'TZNAME_MAX'.
'_SC_NGROUPS_MAX'
Inquire about the parameter corresponding to 'NGROUPS_MAX'.
'_SC_JOB_CONTROL'
Inquire about the parameter corresponding to '_POSIX_JOB_CONTROL'.
'_SC_SAVED_IDS'
Inquire about the parameter corresponding to '_POSIX_SAVED_IDS'.
'_SC_VERSION'
Inquire about the parameter corresponding to '_POSIX_VERSION'.
'_SC_CLK_TCK'
Inquire about the number of clock ticks per second; *note CPU
Time::. The corresponding parameter 'CLK_TCK' is obsolete.
'_SC_CHARCLASS_NAME_MAX'
Inquire about the parameter corresponding to maximal length allowed
for a character class name in an extended locale specification.
These extensions are not yet standardized and so this option is not
standardized as well.
'_SC_REALTIME_SIGNALS'
Inquire about the parameter corresponding to
'_POSIX_REALTIME_SIGNALS'.
'_SC_PRIORITY_SCHEDULING'
Inquire about the parameter corresponding to
'_POSIX_PRIORITY_SCHEDULING'.
'_SC_TIMERS'
Inquire about the parameter corresponding to '_POSIX_TIMERS'.
'_SC_ASYNCHRONOUS_IO'
Inquire about the parameter corresponding to
'_POSIX_ASYNCHRONOUS_IO'.
'_SC_PRIORITIZED_IO'
Inquire about the parameter corresponding to
'_POSIX_PRIORITIZED_IO'.
'_SC_SYNCHRONIZED_IO'
Inquire about the parameter corresponding to
'_POSIX_SYNCHRONIZED_IO'.
'_SC_FSYNC'
Inquire about the parameter corresponding to '_POSIX_FSYNC'.
'_SC_MAPPED_FILES'
Inquire about the parameter corresponding to '_POSIX_MAPPED_FILES'.
'_SC_MEMLOCK'
Inquire about the parameter corresponding to '_POSIX_MEMLOCK'.
'_SC_MEMLOCK_RANGE'
Inquire about the parameter corresponding to
'_POSIX_MEMLOCK_RANGE'.
'_SC_MEMORY_PROTECTION'
Inquire about the parameter corresponding to
'_POSIX_MEMORY_PROTECTION'.
'_SC_MESSAGE_PASSING'
Inquire about the parameter corresponding to
'_POSIX_MESSAGE_PASSING'.
'_SC_SEMAPHORES'
Inquire about the parameter corresponding to '_POSIX_SEMAPHORES'.
'_SC_SHARED_MEMORY_OBJECTS'
Inquire about the parameter corresponding to
'_POSIX_SHARED_MEMORY_OBJECTS'.
'_SC_AIO_LISTIO_MAX'
Inquire about the parameter corresponding to
'_POSIX_AIO_LISTIO_MAX'.
'_SC_AIO_MAX'
Inquire about the parameter corresponding to '_POSIX_AIO_MAX'.
'_SC_AIO_PRIO_DELTA_MAX'
Inquire the value by which a process can decrease its asynchronous
I/O priority level from its own scheduling priority. This
corresponds to the run-time invariant value 'AIO_PRIO_DELTA_MAX'.
'_SC_DELAYTIMER_MAX'
Inquire about the parameter corresponding to
'_POSIX_DELAYTIMER_MAX'.
'_SC_MQ_OPEN_MAX'
Inquire about the parameter corresponding to '_POSIX_MQ_OPEN_MAX'.
'_SC_MQ_PRIO_MAX'
Inquire about the parameter corresponding to '_POSIX_MQ_PRIO_MAX'.
'_SC_RTSIG_MAX'
Inquire about the parameter corresponding to '_POSIX_RTSIG_MAX'.
'_SC_SEM_NSEMS_MAX'
Inquire about the parameter corresponding to
'_POSIX_SEM_NSEMS_MAX'.
'_SC_SEM_VALUE_MAX'
Inquire about the parameter corresponding to
'_POSIX_SEM_VALUE_MAX'.
'_SC_SIGQUEUE_MAX'
Inquire about the parameter corresponding to '_POSIX_SIGQUEUE_MAX'.
'_SC_TIMER_MAX'
Inquire about the parameter corresponding to '_POSIX_TIMER_MAX'.
'_SC_PII'
Inquire about the parameter corresponding to '_POSIX_PII'.
'_SC_PII_XTI'
Inquire about the parameter corresponding to '_POSIX_PII_XTI'.
'_SC_PII_SOCKET'
Inquire about the parameter corresponding to '_POSIX_PII_SOCKET'.
'_SC_PII_INTERNET'
Inquire about the parameter corresponding to '_POSIX_PII_INTERNET'.
'_SC_PII_OSI'
Inquire about the parameter corresponding to '_POSIX_PII_OSI'.
'_SC_SELECT'
Inquire about the parameter corresponding to '_POSIX_SELECT'.
'_SC_UIO_MAXIOV'
Inquire about the parameter corresponding to '_POSIX_UIO_MAXIOV'.
'_SC_PII_INTERNET_STREAM'
Inquire about the parameter corresponding to
'_POSIX_PII_INTERNET_STREAM'.
'_SC_PII_INTERNET_DGRAM'
Inquire about the parameter corresponding to
'_POSIX_PII_INTERNET_DGRAM'.
'_SC_PII_OSI_COTS'
Inquire about the parameter corresponding to '_POSIX_PII_OSI_COTS'.
'_SC_PII_OSI_CLTS'
Inquire about the parameter corresponding to '_POSIX_PII_OSI_CLTS'.
'_SC_PII_OSI_M'
Inquire about the parameter corresponding to '_POSIX_PII_OSI_M'.
'_SC_T_IOV_MAX'
Inquire the value of the value associated with the 'T_IOV_MAX'
variable.
'_SC_THREADS'
Inquire about the parameter corresponding to '_POSIX_THREADS'.
'_SC_THREAD_SAFE_FUNCTIONS'
Inquire about the parameter corresponding to
'_POSIX_THREAD_SAFE_FUNCTIONS'.
'_SC_GETGR_R_SIZE_MAX'
Inquire about the parameter corresponding to
'_POSIX_GETGR_R_SIZE_MAX'.
'_SC_GETPW_R_SIZE_MAX'
Inquire about the parameter corresponding to
'_POSIX_GETPW_R_SIZE_MAX'.
'_SC_LOGIN_NAME_MAX'
Inquire about the parameter corresponding to
'_POSIX_LOGIN_NAME_MAX'.
'_SC_TTY_NAME_MAX'
Inquire about the parameter corresponding to '_POSIX_TTY_NAME_MAX'.
'_SC_THREAD_DESTRUCTOR_ITERATIONS'
Inquire about the parameter corresponding to
'_POSIX_THREAD_DESTRUCTOR_ITERATIONS'.
'_SC_THREAD_KEYS_MAX'
Inquire about the parameter corresponding to
'_POSIX_THREAD_KEYS_MAX'.
'_SC_THREAD_STACK_MIN'
Inquire about the parameter corresponding to
'_POSIX_THREAD_STACK_MIN'.
'_SC_THREAD_THREADS_MAX'
Inquire about the parameter corresponding to
'_POSIX_THREAD_THREADS_MAX'.
'_SC_THREAD_ATTR_STACKADDR'
Inquire about the parameter corresponding to
a '_POSIX_THREAD_ATTR_STACKADDR'.
'_SC_THREAD_ATTR_STACKSIZE'
Inquire about the parameter corresponding to
'_POSIX_THREAD_ATTR_STACKSIZE'.
'_SC_THREAD_PRIORITY_SCHEDULING'
Inquire about the parameter corresponding to
'_POSIX_THREAD_PRIORITY_SCHEDULING'.
'_SC_THREAD_PRIO_INHERIT'
Inquire about the parameter corresponding to
'_POSIX_THREAD_PRIO_INHERIT'.
'_SC_THREAD_PRIO_PROTECT'
Inquire about the parameter corresponding to
'_POSIX_THREAD_PRIO_PROTECT'.
'_SC_THREAD_PROCESS_SHARED'
Inquire about the parameter corresponding to
'_POSIX_THREAD_PROCESS_SHARED'.
'_SC_2_C_DEV'
Inquire about whether the system has the POSIX.2 C compiler
command, 'c89'.
'_SC_2_FORT_DEV'
Inquire about whether the system has the POSIX.2 Fortran compiler
command, 'fort77'.
'_SC_2_FORT_RUN'
Inquire about whether the system has the POSIX.2 'asa' command to
interpret Fortran carriage control.
'_SC_2_LOCALEDEF'
Inquire about whether the system has the POSIX.2 'localedef'
command.
'_SC_2_SW_DEV'
Inquire about whether the system has the POSIX.2 commands 'ar',
'make', and 'strip'.
'_SC_BC_BASE_MAX'
Inquire about the maximum value of 'obase' in the 'bc' utility.
'_SC_BC_DIM_MAX'
Inquire about the maximum size of an array in the 'bc' utility.
'_SC_BC_SCALE_MAX'
Inquire about the maximum value of 'scale' in the 'bc' utility.
'_SC_BC_STRING_MAX'
Inquire about the maximum size of a string constant in the 'bc'
utility.
'_SC_COLL_WEIGHTS_MAX'
Inquire about the maximum number of weights that can necessarily be
used in defining the collating sequence for a locale.
'_SC_EXPR_NEST_MAX'
Inquire about the maximum number of expressions nested within
parentheses when using the 'expr' utility.
'_SC_LINE_MAX'
Inquire about the maximum size of a text line that the POSIX.2 text
utilities can handle.
'_SC_EQUIV_CLASS_MAX'
Inquire about the maximum number of weights that can be assigned to
an entry of the 'LC_COLLATE' category 'order' keyword in a locale
definition. The GNU C Library does not presently support locale
definitions.
'_SC_VERSION'
Inquire about the version number of POSIX.1 that the library and
kernel support.
'_SC_2_VERSION'
Inquire about the version number of POSIX.2 that the system
utilities support.
'_SC_PAGESIZE'
Inquire about the virtual memory page size of the machine.
'getpagesize' returns the same value (*note Query Memory
Parameters::).
'_SC_NPROCESSORS_CONF'
Inquire about the number of configured processors.
'_SC_NPROCESSORS_ONLN'
Inquire about the number of processors online.
'_SC_PHYS_PAGES'
Inquire about the number of physical pages in the system.
'_SC_AVPHYS_PAGES'
Inquire about the number of available physical pages in the system.
'_SC_ATEXIT_MAX'
Inquire about the number of functions which can be registered as
termination functions for 'atexit'; *note Cleanups on Exit::.
'_SC_XOPEN_VERSION'
Inquire about the parameter corresponding to '_XOPEN_VERSION'.
'_SC_XOPEN_XCU_VERSION'
Inquire about the parameter corresponding to '_XOPEN_XCU_VERSION'.
'_SC_XOPEN_UNIX'
Inquire about the parameter corresponding to '_XOPEN_UNIX'.
'_SC_XOPEN_REALTIME'
Inquire about the parameter corresponding to '_XOPEN_REALTIME'.
'_SC_XOPEN_REALTIME_THREADS'
Inquire about the parameter corresponding to
'_XOPEN_REALTIME_THREADS'.
'_SC_XOPEN_LEGACY'
Inquire about the parameter corresponding to '_XOPEN_LEGACY'.
'_SC_XOPEN_CRYPT'
Inquire about the parameter corresponding to '_XOPEN_CRYPT'.
'_SC_XOPEN_ENH_I18N'
Inquire about the parameter corresponding to '_XOPEN_ENH_I18N'.
'_SC_XOPEN_SHM'
Inquire about the parameter corresponding to '_XOPEN_SHM'.
'_SC_XOPEN_XPG2'
Inquire about the parameter corresponding to '_XOPEN_XPG2'.
'_SC_XOPEN_XPG3'
Inquire about the parameter corresponding to '_XOPEN_XPG3'.
'_SC_XOPEN_XPG4'
Inquire about the parameter corresponding to '_XOPEN_XPG4'.
'_SC_CHAR_BIT'
Inquire about the number of bits in a variable of type 'char'.
'_SC_CHAR_MAX'
Inquire about the maximum value which can be stored in a variable
of type 'char'.
'_SC_CHAR_MIN'
Inquire about the minimum value which can be stored in a variable
of type 'char'.
'_SC_INT_MAX'
Inquire about the maximum value which can be stored in a variable
of type 'int'.