man2/getsid.2

   1 .\" Copyright (C) 1996 Andries Brouwer (aeb@cwi.nl)
   2 .\" and Copyright (C) 2016 Michael Kerrisk <mtk.manpages@gmail.com>
   3 .\"
   4 .\" SPDX-License-Identifier: GPL-2.0-or-later
   5 .\"
   6 .\" Modified Thu Oct 31 14:18:40 1996 by Eric S. Raymond <esr@y\thyrsus.com>
   7 .\" Modified 2001-12-17, aeb
   8 .TH getsid 2 (date) "Linux man-pages (unreleased)"
   9 .SH NAME
  10 getsid \- get session ID
  11 .SH LIBRARY
  12 Standard C library
  13 .RI ( libc ", " \-lc )
  14 .SH SYNOPSIS
  15 .nf
  16 .B #include <unistd.h>
  17 .P
  18 .BI "pid_t getsid(pid_t" " pid" );
  19 .fi
  20 .P
  21 .RS -4
  22 Feature Test Macro Requirements for glibc (see
  23 .BR feature_test_macros (7)):
  24 .RE
  25 .P
  26 .BR getsid ():
  27 .nf
  28     _XOPEN_SOURCE >= 500
  29 .\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
  30         || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
  31 .fi
  32 .SH DESCRIPTION
  33 .BR getsid ()
  34 returns the session ID of the process with process ID
  35 .IR pid .
  36 If
  37 .I pid
  38 is 0,
  39 .BR getsid ()
  40 returns the session ID of the calling process.
  41 .SH RETURN VALUE
  42 On success, a session ID is returned.
  43 On error, \fI(pid_t)\ \-1\fP is returned, and
  44 .I errno
  45 is set to indicate the error.
  46 .SH ERRORS
  47 .TP
  48 .B EPERM
  49 A process with process ID
  50 .I pid
  51 exists, but it is not in the same session as the calling process,
  52 and the implementation considers this an error.
  53 .TP
  54 .B ESRCH
  55 No process with process ID
  56 .I pid
  57 was found.
  58 .SH VERSIONS
  59 Linux does not return
  60 .BR EPERM .
  61 .SH STANDARDS
  62 POSIX.1-2008.
  63 .SH HISTORY
  64 POSIX.1-2001, SVr4.
  65 Linux 2.0.
  66 .\" Linux has this system call since Linux 1.3.44.
  67 .\" There is libc support since libc 5.2.19.
  68 .SH NOTES
  69 See
  70 .BR credentials (7)
  71 for a description of sessions and session IDs.
  72 .SH SEE ALSO
  73 .BR getpgid (2),
  74 .BR setsid (2),
  75 .BR credentials (7)