The _exit function is the primitive used for process termination
by exit. It is declared in the header file unistd.h.
— Function: void _exit (int status)
The _exit function is the primitive for causing a process to
terminate with status status. Calling this function does not
execute cleanup functions registered with atexit or
on_exit.
— Function: void _Exit (int status)
The _Exit function is the ISO C equivalent to _exit.
The ISO C committee members were not sure whether the definitions of
_exit and _Exit were compatible so they have not used the
POSIX name.
This function was introduced in ISO C99 and is declared in
stdlib.h.
When a process terminates for any reason—either because the program
terminates, or as a result of a signal—the
following things happen:
All open file descriptors in the process are closed. See Low-Level I/O.
Note that streams are not flushed automatically when the process
terminates; see I/O on Streams.
A process exit status is saved to be reported back to the parent process
via wait or waitpid; see Process Completion. If the
program exited, this status includes as its low-order 8 bits the program
exit status.
Any child processes of the process being terminated are assigned a new
parent process. (On most systems, including GNU, this is the init
process, with process ID 1.)
A SIGCHLD signal is sent to the parent process.
If the process is a session leader that has a controlling terminal, then
a SIGHUP signal is sent to each process in the foreground job,
and the controlling terminal is disassociated from that session.
See Job Control.
If termination of a process causes a process group to become orphaned,
and any member of that process group is stopped, then a SIGHUP
signal and a SIGCONT signal are sent to each process in the
group. See Job Control.
Published under the terms of the GNU General Public License
