1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)getpgrp.2 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD: src/lib/libc/sys/getpgrp.2,v 1.11.2.6 2001/12/14 18:34:00 ru Exp $ 34.\" $DragonFly: src/lib/libc/sys/getpgrp.2,v 1.4 2007/02/25 18:35:05 swildner Exp $ 35.\" 36.Dd June 4, 1993 37.Dt GETPGRP 2 38.Os 39.Sh NAME 40.Nm getpgrp , 41.Nm getpgid 42.Nd get process group 43.Sh LIBRARY 44.Lb libc 45.Sh SYNOPSIS 46.In unistd.h 47.Ft pid_t 48.Fn getpgrp void 49.Ft pid_t 50.Fn getpgid "pid_t pid" 51.Sh DESCRIPTION 52The process group of the current process is returned by 53.Fn getpgrp . 54The process group of the process identified by 55.Fa pid 56is returned by 57.Fn getpgid . 58If 59.Fa pid 60is zero, 61.Fn getpgid 62returns the process group of the current process. 63.Pp 64Process groups are used for distribution of signals, and 65by terminals to arbitrate requests for their input: processes 66that have the same process group as the terminal are foreground 67and may read, while others will block with a signal if they attempt 68to read. 69.Pp 70This call is thus used by programs such as 71.Xr csh 1 72to create 73process groups 74in implementing job control. 75The 76.Fn tcgetpgrp 77and 78.Fn tcsetpgrp 79calls 80are used to get/set the process group of the control terminal. 81.Sh RETURN VALUES 82The 83.Fn getpgrp 84call always succeeds. 85Upon successful completion, the 86.Fn getpgid 87call returns the process group of the specified process; 88otherwise, it returns a value of \-1 and sets 89.Va errno 90to indicate the error. 91.Sh COMPATIBILITY 92This version of 93.Fn getpgrp 94differs from past Berkeley versions by not taking a 95.Fa "pid_t pid" 96argument. 97This incompatibility is required by 98.St -p1003.1-90 . 99.Pp 100From the 101.St -p1003.1-90 102Rationale: 103.Pp 104.Bx 4.3 105provides a 106.Fn getpgrp 107function that returns the process group ID for a specified process. 108Although this function is used to support job control, all known 109job-control shells always specify the calling process with this 110function. 111Thus, the simpler 112.At V 113.Fn getpgrp 114suffices, and the added complexity of the 115.Bx 4.3 116.Fn getpgrp 117has been omitted from POSIX.1. 118The old functionality is available from the 119.Fn getpgid 120function. 121.Sh ERRORS 122.Fn getpgid 123will succeed unless: 124.Bl -tag -width Er 125.It Bq Er ESRCH 126there is no process whose process ID equals 127.Fa pid 128.El 129.Sh SEE ALSO 130.Xr getsid 2 , 131.Xr setpgid 2 , 132.Xr termios 4 133.Sh STANDARDS 134The 135.Fn getpgrp 136function call is expected to conform to 137.St -p1003.1-90 . 138.Sh HISTORY 139The 140.Fn getpgrp 141function call appeared in 142.Bx 4.0 . 143The 144.Fn getpgid 145function call is derived from its usage in System V Release 4. 146