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.\"     @(#)setpgid.2	8.1 (Berkeley) 6/4/93
.\"
.Dd $Mdocdate: May 24 2014 $
.Dt SETPGID 2
.Os
.Sh NAME
.Nm setpgid ,
.Nm setpgrp
.Nd set process group
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fn setpgid "pid_t pid" "pid_t pgrp"
.Ft int
.Fn setpgrp "pid_t pid" "pid_t pgrp"
.Sh DESCRIPTION
.Fn setpgid
sets the process group of the specified process
.Ar pid
to the specified
.Ar pgrp .
If
.Ar pid
is zero, then the call applies to the current process.
If
.Ar pgrp
is zero, the process ID of the specified process is used.
.Sh RETURN VALUES
.Fn setpgid
returns 0 when the operation was successful.
If the request failed, \-1 is returned and the global variable
.Va errno
indicates the reason.
.Sh ERRORS
.Fn setpgid
will fail and the process group will not be altered if:
.Bl -tag -width Er
.It Bq Er EACCES
The value of the
.Fa pid
argument matches the process ID of a child process of the calling process,
and the child process has successfully executed one of the exec functions.
.It Bq Er EINVAL
The value of the
.Fa pgrp
argument is less than zero.
.It Bq Er EPERM
The requested process is a descendant of the calling process, and
is either a session leader or not in the same session as the calling
process.
.It Bq Er EPERM
The value of the
.Fa pgrp
argument is neither the PID of the process indicated by the
.Fa pid
argument nor the process group ID of an existing process group in
the same session as the calling process.
.It Bq Er ESRCH
The value of the
.Fa pid
argument does not match the process ID of the calling process or of a
descendant of the calling process.
.El
.Sh SEE ALSO
.Xr getpgrp 2 ,
.Xr setsid 2
.Sh STANDARDS
.Fn setpgrp
is identical to
.Fn setpgid ,
and is retained for calling convention compatibility with historical
versions of
.Bx .
.Pp
The
.Fn setpgid
function conforms to
.St -p1003.1-2008 .