minix/lib/libc/sys/getpgrp.2
Ben Gras 2fe8fb192f Full switch to clang/ELF. Drop ack. Simplify.
There is important information about booting non-ack images in
docs/UPDATING. ack/aout-format images can't be built any more, and
booting clang/ELF-format ones is a little different. Updating to the
new boot monitor is recommended.

Changes in this commit:

	. drop boot monitor -> allowing dropping ack support
	. facility to copy ELF boot files to /boot so that old boot monitor
	  can still boot fairly easily, see UPDATING
	. no more ack-format libraries -> single-case libraries
	. some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases
	. drop several ack toolchain commands, but not all support
	  commands (e.g. aal is gone but acksize is not yet).
	. a few libc files moved to netbsd libc dir
	. new /bin/date as minix date used code in libc/
	. test compile fix
	. harmonize includes
	. /usr/lib is no longer special: without ack, /usr/lib plays no
	  kind of special bootstrapping role any more and bootstrapping
	  is done exclusively through packages, so releases depend even
	  less on the state of the machine making them now.
	. rename nbsd_lib* to lib*
	. reduce mtree
2012-02-14 14:52:02 +01:00

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.\" $NetBSD: getpgrp.2,v 1.23 2009/03/23 14:11:27 joerg Exp $
.\"
.\" Copyright (c) 1983, 1991, 1993
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.\" @(#)getpgrp.2 8.1 (Berkeley) 6/4/93
.\"
.Dd August 11, 2002
.Dt GETPGRP 2
.Os
.Sh NAME
.Nm getpgrp ,
.Nm getpgid
.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
.Fa pid
process is returned by
.Fn getpgid .
.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 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 ERRORS
.Fn getpgrp
always succeeds, however
.Fn getpgid
will succeed unless:
.Bl -tag -width Er
.It Bq Er ESRCH
if there is no process with a process ID equal to
.Fa pid .
.El
.Sh SEE ALSO
.Xr setpgid 2 ,
.Xr termios 4
.Sh STANDARDS
The
.Fn getpgrp
function conforms to
.St -p1003.1-88 .
.Sh HISTORY
The
.Fn getpgrp
function call appeared in
.Bx 4.0 .
The
.Fn getpgid
function call is derived from its usage in
.At V.4 ,
and first appeared in
.Nx 1.3 .
.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:
.Lp
.Bx 4.3
provides a
.Fn getpgrp
function 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 System 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
function.