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.\" Copyright (C) 1996 Andries Brouwer (aeb@cwi.nl)
.\"
.\" This is free documentation; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License as
.\" published by the Free Software Foundation; either version 2 of
.\" the License, or (at your option) any later version.
.\"
.\" The GNU General Public License's references to "object code"
.\" and "executables" are to be interpreted as the output of any
.\" document formatting or typesetting system, including
.\" intermediate and printed output.
.\"
.\" This manual is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
.\" GNU General Public License for more details.
.\"
.\" You should have received a copy of the GNU General Public
.\" License along with this manual; if not, write to the Free
.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
.\" USA.
.\"
.\" Modified Thu Oct 31 14:18:40 1996 by Eric S. Raymond <esr@y\thyrsus.com>
.\" Modified 2001-12-17, aeb
.TH GETSID 2 2001-12-17 "Linux 2.5.0" "Linux Programmer's Manual"
.SH NAME
getsid \- get session ID
.SH SYNOPSIS
.B #include <unistd.h>
.sp
.BI "pid_t getsid(pid_t" " pid" );
.SH DESCRIPTION
.B getsid(0)
returns the session ID of the calling process.
.BI getsid( p )
returns the session ID of the process with process ID
.IR p .
(The session ID of a process is the process group ID of the
session leader.)
On error, (pid_t) \-1 will be returned, and
.I errno
is set appropriately.
.SH ERRORS
.TP
.B EPERM
A process with process ID
.I p
exists, but it is not in the same session as the current process,
and the implementation considers this an error.
.TP
.B ESRCH
No process with process ID
.I p
was found.
.SH "CONFORMING TO"
SVr4, POSIX 1003.1-2001.
.SH NOTES
Linux does not return EPERM.
.LP
Linux has this system call since Linux 1.3.44.
There is libc support since libc 5.2.19.
.LP
To get the prototype under glibc, define both _XOPEN_SOURCE and
_XOPEN_SOURCE_EXTENDED, or use "#define _XOPEN_SOURCE \fIn\fP"
for some integer \fIn\fP larger than or equal to 500.
.SH "SEE ALSO"
.BR getpgid (2),
.BR setsid (2)
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