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+.\" Copyright (c) 1983, 1991, 1993
+.\"	The Regents of the University of California.  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.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"     @(#)getpgrp.2	8.1 (Berkeley) 6/4/93
+.\" $FreeBSD$
+.\"
+.Dd June 4, 1993
+.Dt GETPGRP 2
+.Os
+.Sh NAME
+.Nm getpgrp
+.Nd get process group
+.Sh LIBRARY
+.Lb libc
+.Sh SYNOPSIS
+.In unistd.h
+.Ft pid_t
+.Fn getpgrp void
+.Ft pid_t
+.Fn getpgid "pid_t pid"
+.Sh DESCRIPTION
+The process group of the current process is returned by
+.Fn getpgrp .
+The process group of the process identified by
+.Fa pid
+is returned by
+.Fn getpgid .
+If
+.Fa pid
+is zero,
+.Fn getpgid
+returns the process group of the current process.
+.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 system 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 RETURN VALUES
+The
+.Fn getpgrp
+system call always succeeds.
+Upon successful completion, the
+.Fn getpgid
+system call returns the process group of the specified process;
+otherwise, it returns a value of \-1 and sets
+.Va errno
+to indicate the error.
+.Sh COMPATIBILITY
+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 -p1003.1-90 .
+.Pp
+From the
+.St -p1003.1-90
+Rationale:
+.Pp
+.Bx 4.3
+provides a
+.Fn getpgrp
+system call 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
+.At V
+.Fn getpgrp
+suffices, and the added complexity of the
+.Bx 4.3
+.Fn getpgrp
+has been omitted from POSIX.1.
+The old functionality is available from the
+.Fn getpgid
+system call.
+.Sh ERRORS
+The
+.Fn getpgid
+system call
+will succeed unless:
+.Bl -tag -width Er
+.It Bq Er ESRCH
+there is no process whose process ID equals
+.Fa pid
+.El
+.Sh SEE ALSO
+.Xr getsid 2 ,
+.Xr setpgid 2 ,
+.Xr termios 4
+.Sh STANDARDS
+The
+.Fn getpgrp
+system call is expected to conform to
+.St -p1003.1-90 .
+.Sh HISTORY
+The
+.Fn getpgrp
+system call appeared in
+.Bx 4.0 .
+The
+.Fn getpgid
+system call is derived from its usage in
+.At V.4 .