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GETPGRP(2)		  FreeBSD System Calls Manual		    GETPGRP(2)

NAME
     getpgrp --	get process group

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <unistd.h>

     pid_t
     getpgrp(void);

     pid_t
     getpgid(pid_t pid);

DESCRIPTION
     The process group of the current process is returned by getpgrp().	 The
     process group of the process identified by	pid is returned	by getpgid().
     If	pid is zero, getpgid() returns the process group of the	current
     process.

     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.

     This system call is thus used by programs such as csh(1) to create
     process groups in implementing job	control.  The tcgetpgrp() and
     tcsetpgrp() calls are used	to get/set the process group of	the control
     terminal.

RETURN VALUES
     The getpgrp() system call always succeeds.	 Upon successful completion,
     the getpgid() system call returns the process group of the	specified
     process; otherwise, it returns a value of -1 and sets errno to indicate
     the error.

COMPATIBILITY
     This version of getpgrp() differs from past Berkeley versions by not tak-
     ing a pid_t pid argument.	This incompatibility is	required by ISO/IEC
     9945-1:1990 ("POSIX.1").

     From the ISO/IEC 9945-1:1990 ("POSIX.1") Rationale:

     4.3BSD provides a 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&T System	V UNIX getpgrp() suf-
     fices, and	the added complexity of	the 4.3BSD getpgrp() has been omitted
     from POSIX.1.  The	old functionality is available from the	getpgid() sys-
     tem call.

ERRORS
     The getpgid() system call will succeed unless:

     [ESRCH]		there is no process whose process ID equals pid

SEE ALSO
     getsid(2),	setpgid(2), termios(4)

STANDARDS
     The getpgrp() system call is expected to conform to ISO/IEC 9945-1:1990
     ("POSIX.1").

HISTORY
     The getpgrp() system call appeared	in 4.0BSD.  The	getpgid() system call
     is	derived	from its usage in AT&T System V	Release	4 UNIX.

FreeBSD	13.0			 June 4, 1993			  FreeBSD 13.0
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | COMPATIBILITY | ERRORS | SEE ALSO | STANDARDS | HISTORY

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