setpgid.3

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)setpgid.3	2.3	9/9/88
.TH setpgid 3
.SH Name
setpgid \- set process group (POSIX)
.SH Syntax
.ft B
.nf
#include <sys/types.h>
int
setpgid(pid, pgrp)
.br
pid_t pid, pgrp;
.fi
.ft R
.SH Description
.NXR "setpgid function"
.NXR "process group" "setting"
The
.PN setpgid
function
is used to either join an existing process group or create a new
process group within the session of the calling process 
(see 
.MS setsid 2 ). 
Upon successful completion, the process group ID of the process that
has a process ID which matches
.I pid
is set to
.IR pgrp .
If
.I pid
is zero, then the call applies to the current process. In addition, if
.I pgrp
is zero, the process ID of the indicated process is used.
.PP
This function is available only in the POSIX environment.
.SH Return Values
The 
.PN setpgid
function
returns 0 when the operation is successful.  If the request fails, \-1 
is returned and the global variable
.PN errno
indicates the reason.
.SH Diagnostics
The
.PN setpgid
function
fails and the process group is not altered if
one of the following occurs:
.TP 15
[EACCES]
The value of the 
.I pid
argument matches the process ID of a child process of the calling process 
and the child process has successfully executed an
.PN exec
function.
.TP 15
[EINVAL]
The value of the 
.I pgrp
argument is less than zero or is not a supported value.
.TP 15
[EPERM]
The process indicated by the
.I pid
argument is a session leader.
.sp
The value of the
.I pid
argument matches the process ID of a child process of the calling process 
and the child process is not in the same session as the calling process.
.sp
The value of the
.I pgrp
argument does not match the process ID of the process indicated by the
.I pid
argument and there is no process with a process group ID that matches the 
value of the
.I pgrp
argument in the same session as the calling process.
.TP 15
[ESRCH]
The value of the
.I pid
argument does not match the process ID of the calling process of a 
child process of the calling process.
.SH See Also
getpgrp(2), setsid(2)