session and set process group ID
() 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
returns the value of the process group ID of the new process group, which is
the same as the process 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:
- 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.
() function is expected to be compliant
with the IEEE Std 1003.1-2008