usr/src/lib/libc/sys/getpgrp.2

.\" Copyright (c) 1983, 1991 Regents of the University of California.
.\" All rights reserved.
.\"
.\" %sccs.include.redist.man%
.\"
.\"     @(#)getpgrp.2   6.7 (Berkeley) %G%
.\"
.Dd
.Dt GETPGRP 2
.Os BSD 4.2
.Sh NAME
.Nm getpgrp
.Nd get process group
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft pid_t
.Fn getpgrp "void"
.Sh DESCRIPTION
The process group of the current process is returned by
.Fn getpgrp .
.Pp
Process groups are used for distribution of signals, and
by terminals to arbitrate requests for their input: processes
that have the same process group as the terminal are foreground
and may read, while others will block with a signal if they attempt
to read.
.Pp
This call is thus used by programs such as
.Xr csh 1
to create
process groups
in implementing job control.
The
.Fn tcgetpgrp
and
.Fn tcsetpgrp
calls
are used to get/set the process group of the control terminal.
.Sh SEE ALSO
.Xr setpgid 2 ,
.Xr termios 4
.Sh HISTORY
The
.Nm
function call appeared in
.Bx 4.0 .
.Sh STANDARDS
The
.Fn getpgrp
function conforms to IEEE Std 1003.1-1988
.Pq Dq Tn POSIX .
.Sh COMPATABILITY
This version of
.Fn getpgrp
differs from past Berkeley versions by not taking a
.Fa "pid_t pid"
argument.
This incompatibility is required by
.St -p1003.1-88 .
.Pp
From the
.St -p1003.1-88
Rationale:
.sp
4.3BSD provides a
.Fn getpgrp
function that returns the process group ID for a specified process.
Although this function is used to support job control, all known
job-control shells always specify the calling process with this
function.
Thus, the simpler System V
.Fn getpgrp
suffices, and the added complexity of the 4.3BSD
.Fn getpgrp
has been omitted from POSIX.1.