1.\" Copyright (c) 1997 Peter Wemm <peter@FreeBSD.org> 2.\" 3.\" Redistribution and use in source and binary forms, with or without 4.\" modification, are permitted provided that the following conditions 5.\" are met: 6.\" 1. Redistributions of source code must retain the above copyright 7.\" notice, this list of conditions and the following disclaimer. 8.\" 2. Redistributions in binary form must reproduce the above copyright 9.\" notice, this list of conditions and the following disclaimer in the 10.\" documentation and/or other materials provided with the distribution. 11.\" 12.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 13.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 14.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 15.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 16.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 17.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 18.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 19.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 20.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 21.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 22.\" SUCH DAMAGE. 23.\" 24.\" $FreeBSD: src/lib/libc/sys/getsid.2,v 1.3.2.5 2001/12/14 18:34:00 ru Exp $ 25.\" $DragonFly: src/lib/libc/sys/getsid.2,v 1.3 2007/06/30 19:03:52 swildner Exp $ 26.\" 27.Dd August 19, 1997 28.Dt GETSID 2 29.Os 30.Sh NAME 31.Nm getsid 32.Nd get process session 33.Sh LIBRARY 34.Lb libc 35.Sh SYNOPSIS 36.In unistd.h 37.Ft pid_t 38.Fn getsid "pid_t pid" 39.Sh DESCRIPTION 40The session ID of the process identified by 41.Fa pid 42is returned by 43.Fn getsid . 44If 45.Fa pid 46is zero, 47.Fn getsid 48returns the session ID of the current process. 49.Sh RETURN VALUES 50Upon successful completion, the function 51.Fn getsid 52returns the session ID of 53the specified process; otherwise, it returns a value of -1 and 54sets 55.Va errno 56to indicate an error. 57.Sh ERRORS 58.Fn getsid 59will succeed unless: 60.Bl -tag -width Er 61.It Bq Er ESRCH 62if there is no process with a process ID equal to 63.Fa pid . 64.El 65.Pp 66Note that an implementation may restrict this function call to 67processes within the same session ID as the calling process. 68.Sh SEE ALSO 69.Xr getpgid 2 , 70.Xr getpgrp 2 , 71.Xr setpgid 2 , 72.Xr setsid 2 , 73.Xr termios 4 74.Sh HISTORY 75The 76.Fn getsid 77function call appeared in 78.Fx 3.0 . 79The 80.Fn getsid 81function call is derived from its usage in 82.At V . 83