SETSID(2) BSD Programmer's Manual SETSID(2)
setsid - create session and set process group ID
The setsid function creates a new session. The calling process is the
session leader of the new session, is the process group leader of a new
process group and has no controlling terminal. The calling process is
the only process in either the session or the process group.
Upon successful completion, the setsid function returns the value of the
process group ID of the new process group, which is the same as the pro-
cess ID of the calling process.
If an error occurs, setsid returns -1 and the global variable errno is
set to indicate the error, as follows:
[EPERM] The calling process is already a process group leader, or
the process group ID of a process other than the calling
process matches the process ID of the calling process.
setpgid(3), tcgetpgrp(3), tcsetpgrp(3)
The setsid function is expected to be compliant with the IEEE
Std1003.1-1988 (``POSIX'') specification.
4.4BSD June 4, 1993 1