atexit.3: Calling _exit(2) terminates processing of exit handlers

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man3/atexit.3

@@ -75,6 +75,13 @@ Functions registered using
 are not called if a process terminates abnormally because
 of the delivery of a signal.
 
+If one of the functions registered functions calls
+.BR _exit (2),
+then any remaining functions are not invoked,
+and the other process termination steps performed by
+.BR exit (3)
+are not performed.
+
 The
 .BR atexit ()
 and