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 1.3 2006/02/17 19:35:06 swildner Exp $ 35.\" 36.Dd June 4, 1993 37.Dt GETPGRP 2 38.Os 39.Sh NAME 40.Nm getpgrp 41.Nd get process group 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In unistd.h 46.Ft pid_t 47.Fn getpgrp void 48.Ft pid_t 49.Fn getpgid "pid_t pid" 50.Sh DESCRIPTION 51The process group of the current process is returned by 52.Fn getpgrp . 53The process group of the process identified by 54.Fa pid 55is returned by 56.Fn getpgid . 57If 58.Fa pid 59is zero, 60.Fn getpgid 61returns the process group of the current process. 62.Pp 63Process groups are used for distribution of signals, and 64by terminals to arbitrate requests for their input: processes 65that have the same process group as the terminal are foreground 66and may read, while others will block with a signal if they attempt 67to read. 68.Pp 69This call is thus used by programs such as 70.Xr csh 1 71to create 72process groups 73in implementing job control. 74The 75.Fn tcgetpgrp 76and 77.Fn tcsetpgrp 78calls 79are used to get/set the process group of the control terminal. 80.Sh RETURN VALUES 81The 82.Fn getpgrp 83call always succeeds. 84Upon successful completion, the 85.Fn getpgid 86call returns the process group of the specified process; 87otherwise, it returns a value of \-1 and sets 88.Va errno 89to indicate the error. 90.Sh COMPATIBILITY 91This version of 92.Fn getpgrp 93differs from past Berkeley versions by not taking a 94.Fa "pid_t pid" 95argument. 96This incompatibility is required by 97.St -p1003.1-90 . 98.Pp 99From the 100.St -p1003.1-90 101Rationale: 102.Pp 103.Bx 4.3 104provides a 105.Fn getpgrp 106function that returns the process group ID for a specified process. 107Although this function is used to support job control, all known 108job-control shells always specify the calling process with this 109function. 110Thus, the simpler 111.At V 112.Fn getpgrp 113suffices, and the added complexity of the 114.Bx 4.3 115.Fn getpgrp 116has been omitted from POSIX.1. 117The old functionality is available from the 118.Fn getpgid 119function. 120.Sh ERRORS 121.Fn getpgid 122will succeed unless: 123.Bl -tag -width Er 124.It Bq Er ESRCH 125there is no process whose process ID equals 126.Fa pid 127.El 128.Sh SEE ALSO 129.Xr getsid 2 , 130.Xr setpgid 2 , 131.Xr termios 4 132.Sh STANDARDS 133The 134.Fn getpgrp 135function call is expected to conform to 136.St -p1003.1-90 . 137.Sh HISTORY 138The 139.Fn getpgrp 140function call appeared in 141.Bx 4.0 . 142The 143.Fn getpgid 144function call is derived from its usage in System V Release 4. 145