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.Dd August 19, 1997 25.Dt GETSID 2 26.Os 27.Sh NAME 28.Nm getsid 29.Nd get process session 30.Sh LIBRARY 31.Lb libc 32.Sh SYNOPSIS 33.In unistd.h 34.Ft pid_t 35.Fn getsid "pid_t pid" 36.Sh DESCRIPTION 37The session ID of the process identified by 38.Fa pid 39is returned by 40.Fn getsid . 41If 42.Fa pid 43is zero, 44.Fn getsid 45returns the session ID of the current process. 46.Sh RETURN VALUES 47Upon successful completion, the 48.Fn getsid 49system call 50returns the session ID of 51the specified process; otherwise, it returns a value of -1 and 52sets errno to indicate an error. 53.Sh ERRORS 54The 55.Fn getsid 56system call 57will succeed unless: 58.Bl -tag -width Er 59.It Bq Er ESRCH 60if there is no process with a process ID equal to 61.Fa pid . 62.El 63.Pp 64Note that an implementation may restrict this system call to 65processes within the same session ID as the calling process. 66.Sh SEE ALSO 67.Xr getpgid 2 , 68.Xr getpgrp 2 , 69.Xr setpgid 2 , 70.Xr setsid 2 , 71.Xr termios 4 72.Sh HISTORY 73The 74.Fn getsid 75system call appeared in 76.Fx 3.0 . 77The 78.Fn getsid 79system call is derived from its usage in 80.At V . 81