.\" Copyright (c) 1994 Christoph M. Robitschko
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"      This product includes software developed by Christoph M. Robitschko
.\" 4. The name of the author may not be used to endorse or promote products
.\"    derived from this software withough specific prior written permission
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.Dd January 28, 1994
.Dt SETSID 2
.Os FreeBSD
.Sh NAME
.Nm setsid
.Nd create session and set process group ID
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Ft pid_t
.Fn setsid
.Sh DESCRIPTION
If the calling process is not a process group leader, the 
.Fn setsid
function creates a new session and a new process group.
The calling process is the session leader and process group leader, and
has no controlling terminal.
The ID of the process group is set to the process ID of the calling process.
The calling process is the only member of the new session and of the new
process group.
.Sh RETURN VALUES
.Fn Setsid
returns the value of the new process group ID when the operation was successful.
If the request failed, -1 is returned and the global variable
.Va errno
indicates the reason.
.Sh ERRORS
.Fn Setsid
will fail if:
.Bl -tag -width indent
.It Bq Er EPERM
The calling process is already a process group leader, or the process group ID
of another process matches the process ID of the calling process.
.El
.Sh SEE ALSO
.Xr getpid 2 ,
.Xr setpgid 2
.Sh STANDARDS
.Fn Setpgid
conforms to IEEE Std 1003.1-1988
.Pq Dq Tn POSIX .