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.\" 35.Dd June 4, 1993 36.Dt GETPGRP 2 37.Os 38.Sh NAME 39.Nm getpgrp 40.Nd get process group 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In unistd.h 45.Ft pid_t 46.Fn getpgrp void 47.Ft pid_t 48.Fn getpgid "pid_t pid" 49.Sh DESCRIPTION 50The process group of the current process is returned by 51.Fn getpgrp . 52The process group of the process identified by 53.Fa pid 54is returned by 55.Fn getpgid . 56If 57.Fa pid 58is zero, 59.Fn getpgid 60returns the process group of the current process. 61.Pp 62Process groups are used for distribution of signals, and 63by terminals to arbitrate requests for their input: processes 64that have the same process group as the terminal are foreground 65and may read, while others will block with a signal if they attempt 66to read. 67.Pp 68This call is thus used by programs such as 69.Xr csh 1 70to create 71process groups 72in implementing job control. 73The 74.Fn tcgetpgrp 75and 76.Fn tcsetpgrp 77calls 78are used to get/set the process group of the control terminal. 79.Sh RETURN VALUES 80The 81.Fn getpgrp 82call always succeeds. 83Upon successful completion, the 84.Fn getpgid 85call returns the process group of the specified process; 86otherwise, it returns a value of \-1 and sets 87.Va errno 88to indicate the error. 89.Sh ERRORS 90.Fn getpgid 91will succeed unless: 92.Bl -tag -width Er 93.It Bq Er ESRCH 94there is no process whose process ID equals 95.Fa pid 96.El 97.Sh SEE ALSO 98.Xr getsid 2 , 99.Xr setpgid 2 , 100.Xr termios 4 101.Sh HISTORY 102The 103.Fn getpgrp 104function call appeared in 105.Bx 4.0 . 106The 107.Fn getpgid 108function call is derived from its usage in System V Release 4. 109.Sh STANDARDS 110The 111.Fn getpgrp 112function call is expected to conform to 113.St -p1003.1-90 . 114.Sh COMPATIBILITY 115This version of 116.Fn getpgrp 117differs from past Berkeley versions by not taking a 118.Fa "pid_t pid" 119argument. 120This incompatibility is required by 121.St -p1003.1-90 . 122.Pp 123From the 124.St -p1003.1-90 125Rationale: 126.Pp 127.Bx 4.3 128provides a 129.Fn getpgrp 130function that returns the process group ID for a specified process. 131Although this function is used to support job control, all known 132job-control shells always specify the calling process with this 133function. 134Thus, the simpler 135.At V 136.Fn getpgrp 137suffices, and the added complexity of the 138.Bx 4.3 139.Fn getpgrp 140has been omitted from POSIX.1. 141The old functionality is available from the 142.Fn getpgid 143function. 144