1.\" $OpenBSD: setsid.2,v 1.15 2023/01/12 12:56:07 jsg Exp $ 2.\" $NetBSD: setsid.2,v 1.3 1995/10/12 15:41:13 jtc Exp $ 3.\" 4.\" Copyright (c) 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)setsid.2 8.1 (Berkeley) 6/4/93 32.\" 33.Dd $Mdocdate: January 12 2023 $ 34.Dt SETSID 2 35.Os 36.Sh NAME 37.Nm setsid 38.Nd create session and set process group ID 39.Sh SYNOPSIS 40.In unistd.h 41.Ft pid_t 42.Fn setsid "void" 43.Sh DESCRIPTION 44The 45.Fn setsid 46function creates a new session. 47The calling process is the session leader of the new session, is the 48process group leader of a new process group and has no controlling 49terminal. 50The calling process is the only process in either the session or the 51process group. 52.Pp 53Upon successful completion, the 54.Fn setsid 55function returns the value of the process group ID of the new process 56group, which is the same as the process ID of the calling process. 57.Sh ERRORS 58If an error occurs, 59.Fn setsid 60returns \-1 and the global variable 61.Va errno 62is set to indicate the error, as follows: 63.Bl -tag -width Er 64.It Bq Er EPERM 65The calling process is already a process group leader, or the process 66group ID of a process other than the calling process matches the process 67ID of the calling process. 68.El 69.Sh SEE ALSO 70.Xr getsid 2 , 71.Xr setpgid 2 , 72.Xr tcgetpgrp 3 , 73.Xr tcsetpgrp 3 74.Sh STANDARDS 75The 76.Fn setsid 77function is compliant with the 78.St -p1003.1-2008 79specification. 80