unistd(4)                 FILE FORMATS                  unistd(4)



NAME
     unistd - header file for symbolic constants

SYNOPSIS
     #include <unistd.h>

DESCRIPTION
     The <unistd.h> header file defines  the  symbolic  constants
     and  structures which are not already defined or declared in
     some other header. The contents of  this  header  are  shown
     below.  The following symbolic constants are defined for the
     access function [see access(2)]:
        ROK   Test for read permission
        WOK   Test for write permission
        XOK   Test for execute (search) permission
        FOK   Test for existence of file
     The constants FOK, ROK, WOK and XOK and the  expressions
     ROK|WOK,  ROK|XOK  and  ROK|WOK|XOK all have distinct
     values.  Declares the constant
        NULL   null pointer
     The following symbolic constants are defined for  the  lockf
     function [see lockf(3C)]:
        FULOCK   Unlock a previously locked region
        FLOCK    Lock a region for exclusive use
        FTLOCK   Test and lock a region for exclusive use
        FTEST    Test a region for other processes locks
     The following symbolic constants are defined for  the  lseek
     [see lseek(2)] and fcntl [see fcntl(2)] functions (they have
     distinct values):
        SEEKSET   Set file offset to offset
        SEEKCUR   Set file offset to current plus offset
        SEEKEND   Set file offset to EOF plus offset
     The following symbolic constants  are  defined  (with  fixed
     values):
        POSIXVERSION   Integer value indicating version
                         of the POSIX standard
        XOPENVERSION   integer value indicating version of the XPG
                         to which system is compliant
     The following symbolic constants  are  defined  to  indicate
     that the option is present:
        POSIXJOBCONTROL   implementation    sup-
                             ports job control
        POSIXSAVEDIDS     the   exec   functions
                             [see exec(2)] save the
                             effective   user   and
                             group









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unistd(4)                 FILE FORMATS                  unistd(4)



        POSIXVDISABLE      terminal special char-
                             acters    defined   in
                             <termios.h> [see  ter-
                             mio(7)]  can  be  dis-
                             abled using this char-
                             acter
     The following symbolic constants  are  defined  for  sysconf
     [see sysconf(3C)]:
        SCARGMAX
        SCCHILDMAX
        SCCLKTCK
        SCJOBCONTROL
        SCNGROUPSMAX
        SCOPENMAX
        SCPAGESIZE
        SCPASSMAX
        SCSAVEDIDS
        SCVERSION
        SCXOPENVERSION
     The following symbolic constants are  defined  for  pathconf
     [see fpathconf(3C)]:
        PCCHOWNRESTRICTED
        PCLINKMAX
        PCMAXCANON
        PCMAXINPUT
        PCNAMEMAX
        PCNOTRUNC
        PCPATHMAX
        PCPIPEBUF
        PCVDISABLE
     The  following  symbolic  constants  are  defined  for  file
     streams:
        STDINFILENO    File number of stdin.  It is 0.
        STDOUTFILENO   File number of stout.  It is 1.
        STDERRFILENO   File number of stderr.  It is 2.
     The following pathnames are defined:
        GFPATH   Pathname of the group file.
        PFPATH   Pathname of the passwd file.

NOTES
     The following values for  constants  are  defined  for  this
     release of System V:
        POSIXVERSION   198808L
        XOPENVERSION        3

SEE ALSO
     access(2), exec(2), fcntl(2), lseek(2), termios(2),
     fpathconf(3C), sysconf(3C), group(4), passwd(4), termio(7).







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