.\" Copyright (C) 1996 Andries Brouwer (aeb@cwi.nl)

.\" and Copyright (C) 2016 Michael Kerrisk <mtk.manpages@gmail.com>

.\"

.\" %%%LICENSE_START(GPLv2+_DOC_FULL)

.\" 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

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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of

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.\" GNU General Public License for more details.

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.\" Modified Thu Oct 31 14:18:40 1996 by Eric S. Raymond <esr@y\thyrsus.com>

.\" Modified 2001-12-17, aeb

.TH GETSID 2 2017-09-15 "Linux" "Linux Programmer's Manual"

.SH NAME

getsid \- get session ID

.SH SYNOPSIS

.B #include <sys/types.h>

.br

.B #include <unistd.h>

.PP

.BI "pid_t getsid(pid_t" " pid" );

.PP

.in -4n

Feature Test Macro Requirements for glibc (see

.BR feature_test_macros (7)):

.in

.PP

.ad l

.PD 0

.BR getsid ():

.RS 4

_XOPEN_SOURCE\ >=\ 500

.\"    || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED

.br

    || /* Since glibc 2.12: */ _POSIX_C_SOURCE\ >=\ 200809L

.RE

.PD

.ad

.SH DESCRIPTION

.I getsid(0)

returns the session ID of the calling process.

.BR getsid ()

returns the session ID of the process with process ID

.IR pid .

If

.I pid

is 0,

.BR getsid ()

returns the session ID of the calling process.

.SH RETURN VALUE

On success, a session ID is returned.

On error, \fI(pid_t)\ \-1\fP will be returned, and

.I errno

is set appropriately.

.SH ERRORS

.TP

.B EPERM

A process with process ID

.I pid

exists, but it is not in the same session as the calling process,

and the implementation considers this an error.

.TP

.B ESRCH

No process with process ID

.I pid

was found.

.SH VERSIONS

This system call is available on Linux since version 2.0.

.\" Linux has this system call since Linux 1.3.44.

.\" There is libc support since libc 5.2.19.

.SH CONFORMING TO

POSIX.1-2001, POSIX.1-2008, SVr4.

.SH NOTES

Linux does not return

.BR EPERM .

.PP

See

.BR credentials (7)

for a description of sessions and session IDs.

.SH SEE ALSO

.BR getpgid (2),

.BR setsid (2),

.BR credentials (7)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.