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.\"     @(#)setpgid.2	8.1 (Berkeley) 6/4/93
.\"
.Dd December 18, 2003
.Dt SETPGID 2
.Os
.Sh NAME
.Nm setpgid ,
.Nm setpgrp
.Nd set process group
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In 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, then the process id of the process specified by
.Ar pid
is used instead.
.Pp
If the invoker is not the super-user, then the affected process
must have the same effective user-id as the invoker or be a descendant
of the invoking process.
.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 effective user ID of the requested process is different
from that of the caller and the process is not a descendant
of 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
child process of the calling process.
.El
.Sh SEE ALSO
.Xr getpgrp 2
.Sh STANDARDS
The
.Fn setpgid
function conforms to
.St -p1003.1-90 .
.Sh COMPATIBILITY
.Fn setpgrp
is identical to
.Fn setpgid ,
and is retained for calling convention compatibility with historical
versions of
.Bx .