mirror of
https://git.FreeBSD.org/src.git
synced 2024-11-26 07:55:01 +00:00
8269e7673c
Remove core system call implementations and documentation to lib/libsys and lib/libsys/<arch> from lib/libc/sys and lib/libc/<arch>/<sys>. Update paths to allow libc to find them in their new home. Reviewed by: kib, emaste, imp Pull Request: https://github.com/freebsd/freebsd-src/pull/908
140 lines
3.8 KiB
Groff
140 lines
3.8 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.Dd June 4, 1993
|
|
.Dt GETPGRP 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm getpgrp
|
|
.Nd get process group
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In unistd.h
|
|
.Ft pid_t
|
|
.Fn getpgrp void
|
|
.Ft pid_t
|
|
.Fn getpgid "pid_t pid"
|
|
.Sh DESCRIPTION
|
|
The process group of the current process is returned by
|
|
.Fn getpgrp .
|
|
The process group of the process identified by
|
|
.Fa pid
|
|
is returned by
|
|
.Fn getpgid .
|
|
If
|
|
.Fa pid
|
|
is zero,
|
|
.Fn getpgid
|
|
returns the process group of the current process.
|
|
.Pp
|
|
Process groups are used for distribution of signals, and
|
|
by terminals to arbitrate requests for their input: processes
|
|
that have the same process group as the terminal are foreground
|
|
and may read, while others will block with a signal if they attempt
|
|
to read.
|
|
.Pp
|
|
This system call is thus used by programs such as
|
|
.Xr csh 1
|
|
to create
|
|
process groups
|
|
in implementing job control.
|
|
The
|
|
.Fn tcgetpgrp
|
|
and
|
|
.Fn tcsetpgrp
|
|
calls
|
|
are used to get/set the process group of the control terminal.
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Fn getpgrp
|
|
system call always succeeds.
|
|
Upon successful completion, the
|
|
.Fn getpgid
|
|
system call returns the process group of the specified process;
|
|
otherwise, it returns a value of \-1 and sets
|
|
.Va errno
|
|
to indicate the error.
|
|
.Sh COMPATIBILITY
|
|
This version of
|
|
.Fn getpgrp
|
|
differs from past Berkeley versions by not taking a
|
|
.Fa "pid_t pid"
|
|
argument.
|
|
This incompatibility is required by
|
|
.St -p1003.1-90 .
|
|
.Pp
|
|
From the
|
|
.St -p1003.1-90
|
|
Rationale:
|
|
.Pp
|
|
.Bx 4.3
|
|
provides a
|
|
.Fn getpgrp
|
|
system call that returns the process group ID for a specified process.
|
|
Although this function is used to support job control, all known
|
|
job-control shells always specify the calling process with this
|
|
function.
|
|
Thus, the simpler
|
|
.At V
|
|
.Fn getpgrp
|
|
suffices, and the added complexity of the
|
|
.Bx 4.3
|
|
.Fn getpgrp
|
|
has been omitted from POSIX.1.
|
|
The old functionality is available from the
|
|
.Fn getpgid
|
|
system call.
|
|
.Sh ERRORS
|
|
The
|
|
.Fn getpgid
|
|
system call
|
|
will succeed unless:
|
|
.Bl -tag -width Er
|
|
.It Bq Er ESRCH
|
|
there is no process whose process ID equals
|
|
.Fa pid
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr getsid 2 ,
|
|
.Xr setpgid 2 ,
|
|
.Xr termios 4
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn getpgrp
|
|
system call is expected to conform to
|
|
.St -p1003.1-90 .
|
|
.Sh HISTORY
|
|
The
|
|
.Fn getpgrp
|
|
system call appeared in
|
|
.Bx 4.0 .
|
|
The
|
|
.Fn getpgid
|
|
system call is derived from its usage in
|
|
.At V.4 .
|