setregid.2

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)setregid.2	8.1	9/11/90
.TH setregid 2
.SH Name
setregid \- set real and effective group ID
.SH Syntax
.B setregid(\fIrgid, egid\fP)
.br
.B int \fIrgid, egid\fP;
.SH Description
.NXR "setregid system call"
.NXR "real group ID" "setting"
.NXR "effective group ID" "setting"
The real and effective group ID's of the current process
are set to the arguments.
.PP
Supplying a value of \-1 for either the real or effective
group ID forces the system to substitute the current
ID for the \-1 parameter.
.SH Environment
.PP
.B BSD
.br 
If the process is superuser, or
.PN rgid
and
.PN egid
matches with the real group ID, the effective group ID, or the saved
set-group-id (as described in
.MS execve 2
), then the real, effective, and saved set-group-id are set to 
.PN rgid ,
.PN egid ,
and
.PN egid ,
respectively.
.PP 
.B POSIX
.br
.B SYSTEM-FIVE
.br 
When your program is compiled in POSIX or SYSTEM-FIVE mode, the
following semantics apply when using the 
.PN setregid
function.
.PP
If the process is the superuser, the real, effective, and saved
set-group-id (as described in 
.MS execve 2
) are set to 
.PN rgid ,
.PN egid ,
and
.PN egid ,
respectively.
.PP
If the process is not the superuser, but the
.PN rgid
and
.PN egid
matches the real group ID, the effective group ID
(only in SYSTEM-FIVE and BSD environment), or the saved set-group-id,
then the effective ID is set to
.PN egid. 
The real group ID and the saved set-group-id are left unchanged.
.SH Return Values
Upon successful completion, a value of zero (0) is returned.  Otherwise,
a value of \-1 is returned, and \fIerrno\fP is set to indicate the error.
.SH Diagnostics
.TP 15
[EPERM]
The current process is not the superuser and the
.PN egid
and
.PN rgid
specified does not match with the real group ID or the effective group
ID (only in SYSTEM-FIVE and BSD environment) or the saved set-group-id.
.SH See Also
getgid(2), setreuid(2), setgid(3)