1.\" $OpenBSD: getpgrp.2,v 1.14 2007/07/21 20:35:28 jmc Exp $ 2.\" $NetBSD: getpgrp.2,v 1.8 1995/02/27 12:33:09 cgd Exp $ 3.\" 4.\" Copyright (c) 1983, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)getpgrp.2 8.1 (Berkeley) 6/4/93 32.\" 33.Dd $Mdocdate: July 21 2007 $ 34.Dt GETPGRP 2 35.Os 36.Sh NAME 37.Nm getpgrp , 38.Nm getpgid 39.Nd get process group 40.Sh SYNOPSIS 41.Fd #include <unistd.h> 42.Ft pid_t 43.Fn getpgrp "void" 44.Ft pid_t 45.Fn getpgid "pid_t pid" 46.Sh DESCRIPTION 47The process group of the current process is returned by 48.Fn getpgrp . 49The process group of the 50.Fa pid 51process is returned by 52.Fn getpgid . 53If 54.Fa pid 55is zero, 56.Fn getpgid 57returns the process group of the current process. 58.Pp 59Process groups are used for distribution of signals, and 60by terminals to arbitrate requests for their input: processes 61that have the same process group as the terminal are foreground 62and may read, while others will block with a signal if they attempt 63to read. 64.Pp 65These calls are thus used by programs such as 66.Xr csh 1 67to create 68process groups 69in implementing job control. 70The 71.Fn tcgetpgrp 72and 73.Fn tcsetpgrp 74calls 75are used to get/set the process group of the control terminal. 76.Sh ERRORS 77.Fn getpgrp 78always succeeds, however 79.Fn getpgid 80will succeed unless: 81.Bl -tag -width Er 82.It Bq Er EPERM 83The current process and the process 84.Fa pid 85are not in the same session. 86.It Bq Er ESRCH 87There is no process with a process ID equal to 88.Fa pid . 89.El 90.Sh SEE ALSO 91.Xr setpgid 2 , 92.Xr termios 4 93.Sh STANDARDS 94This version of 95.Fn getpgrp 96differs from past Berkeley versions by not taking a 97.Fa "pid_t pid" 98argument. 99This incompatibility is required by 100.St -p1003.1-88 . 101.Pp 102From the 103.St -p1003.1-88 104Rationale: 105.Pp 106.Bx 4.3 107provides a 108.Fn getpgrp 109function that returns the process group ID for a specified process. 110Although this function is used to support job control, all known 111job-control shells always specify the calling process with this 112function. 113Thus, the simpler System V 114.Fn getpgrp 115suffices, and the added complexity of the 116.Bx 4.3 117.Fn getpgrp 118has been omitted from POSIX.1. 119.Pp 120The 121.Fn getpgrp 122function conforms to 123.St -p1003.1-88 . 124The 125.Fn getpgid 126function call is derived from its usage in System V Release 4, and 127first appeared in 128.Nx 1.2a . 129.Sh HISTORY 130The 131.Fn getpgrp 132function call appeared in 133.Bx 4.0 . 134