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`exit'--end program execution

     #include <stdlib.h>
     void exit(int CODE);
Use `exit' to return control from a program to the host operating
environment.  Use the argument CODE to pass an exit status to the
operating environment: two particular values, `EXIT_SUCCESS' and
`EXIT_FAILURE', are defined in ``stdlib.h'' to indicate success or
failure in a portable fashion.
   `exit' does two kinds of cleanup before ending execution of your
program.  First, it calls all application-defined cleanup functions you
have enrolled with `atexit'.  Second, files and streams are cleaned up:
any pending output is delivered to the host system, each open file or
stream is closed, and files created by `tmpfile' are deleted.
`exit' does not return to its caller.
ANSI C requires `exit', and specifies that `EXIT_SUCCESS' and
`EXIT_FAILURE' must be defined.
   Supporting OS subroutines required: `_exit'.