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.Dd June 4, 1993 29.Dt GETPGRP 2 30.Os 31.Sh NAME 32.Nm getpgrp 33.Nd get process group 34.Sh LIBRARY 35.Lb libc 36.Sh SYNOPSIS 37.In unistd.h 38.Ft pid_t 39.Fn getpgrp void 40.Ft pid_t 41.Fn getpgid "pid_t pid" 42.Sh DESCRIPTION 43The process group of the current process is returned by 44.Fn getpgrp . 45The process group of the process identified by 46.Fa pid 47is returned by 48.Fn getpgid . 49If 50.Fa pid 51is zero, 52.Fn getpgid 53returns the process group of the current process. 54.Pp 55Process groups are used for distribution of signals, and 56by terminals to arbitrate requests for their input: processes 57that have the same process group as the terminal are foreground 58and may read, while others will block with a signal if they attempt 59to read. 60.Pp 61This system call is thus used by programs such as 62.Xr csh 1 63to create 64process groups 65in implementing job control. 66The 67.Fn tcgetpgrp 68and 69.Fn tcsetpgrp 70calls 71are used to get/set the process group of the control terminal. 72.Sh RETURN VALUES 73The 74.Fn getpgrp 75system call always succeeds. 76Upon successful completion, the 77.Fn getpgid 78system call returns the process group of the specified process; 79otherwise, it returns a value of \-1 and sets 80.Va errno 81to indicate the error. 82.Sh COMPATIBILITY 83This version of 84.Fn getpgrp 85differs from past Berkeley versions by not taking a 86.Fa "pid_t pid" 87argument. 88This incompatibility is required by 89.St -p1003.1-90 . 90.Pp 91From the 92.St -p1003.1-90 93Rationale: 94.Pp 95.Bx 4.3 96provides a 97.Fn getpgrp 98system call that returns the process group ID for a specified process. 99Although this function is used to support job control, all known 100job-control shells always specify the calling process with this 101function. 102Thus, the simpler 103.At V 104.Fn getpgrp 105suffices, and the added complexity of the 106.Bx 4.3 107.Fn getpgrp 108has been omitted from POSIX.1. 109The old functionality is available from the 110.Fn getpgid 111system call. 112.Sh ERRORS 113The 114.Fn getpgid 115system call 116will succeed unless: 117.Bl -tag -width Er 118.It Bq Er ESRCH 119there is no process whose process ID equals 120.Fa pid 121.El 122.Sh SEE ALSO 123.Xr getsid 2 , 124.Xr setpgid 2 , 125.Xr termios 4 126.Sh STANDARDS 127The 128.Fn getpgrp 129system call is expected to conform to 130.St -p1003.1-90 . 131.Sh HISTORY 132The 133.Fn getpgrp 134system call appeared in 135.Bx 4.0 . 136The 137.Fn getpgid 138system call is derived from its usage in 139.At V.4 . 140