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