Exits is the conventional way to terminate a process.
_Exits also terminates a process but does not call the registered
can never return.
Msg conventionally includes a brief (maximum length
ERRLEN) explanation of the reason for
exiting, or a null pointer or empty string to indicate normal termination.
The string is passed to the parent process, prefixed by the name and process
id of the exiting process, when the parent does a
msg as an argument,
exits calls in reverse order all the functions
fn as a function to be called by
exits. It returns zero if it failed,
A typical use is to register a cleanup routine for an I/O package.
To simplify programs that fork or share memory,
exits only calls those
atexit-registered functions that were registered by the same
process as that calling
atexit twice (or more) with the same function argument causes
exits to invoke the function twice (or more).
There is a limit to the number of exit functions
that will be recorded;
atexit returns 0 if that limit has been reached.
Atexitdont cancels a previous registration of an exit function.
Because of limitations of Unix, the exit status of a
process can only be an 8-bit integer.
_exits treat null or empty exit status as exit code 0
exitcode to translate any other string into an exit code.
By default, the library provides an
exitcode that maps all messages to 1.
Applications may find it useful to provide their own
Exit codes 97 through 99 are used by the thread library to signal
internal synchronization errors between the main program
and a proxy process that implements backgrounding.
To avoid name conflicts with the underlying system,
atexitdont are preprocessor macros defined as