setsid.2

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 2 代码 · 共 52 行

.\" SCCSID: @(#)setsid.2	2.3	8/10/87
.TH setsid 2
.SH Name
setsid \- POSIX create session and set process group ID
.SH Syntax
.ft B
.nf
#include <sys/types.h>
pid_t
setsid()
.fi
.ft R
.SH Description
.NXR "setsid system call"
.NXR "session" "creating"
The
.PN setsid
system call
creates a new session, if the calling process is 
not a process group leader.
The calling process is the session leader of the 
new session, the process group 
leader of the new process group, and does 
not have a controlling terminal.
The process group ID of the calling process is set 
equal to the process ID of the calling process.
.SH Return Values
Upon successful completion, the
.PN setsid
system call
returns the value of the process group ID of the calling process.
If the 
.PN setsid
system call fails, \-1 is returned, and the global
variable
.I errno
indicates the reason.
.SH Diagnostics
The
.PN setsid
system call
fails and a new session is not created if
the following occurs:
.TP 15
[EPERM]
The calling process is already a process group leader.
.sp
The process group ID of a process other than the calling process
matches the process ID of the calling process.
.SH See Also
getpgrp(2), setpgid(3)