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 NAME     
 |  |  |  | exits, _exits, exitcode, atexit, atexitdont – terminate process,
    process cleanup 
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 SYNOPSIS     
 |  |  |  | #include <u.h> #include <libc.h> 
    
    
    void    _exits(char *msg)
 void    exits(char *msg)
 int    exitcode(char *msg)
 int    atexit(void(*)(void))
 void    atexitdont(void(*)(void))
 
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 DESCRIPTION     
 |  |  |  | Exits is the conventional way to terminate a process. _Exits also
    terminates a process but does not call the registered atexit handlers
    (q.v.). They 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 wait(3). 
    
    
    Before calling _exits with msg as an argument, exits calls in
    reverse order all the functions recorded by atexit. 
    
    
    Atexit records fn as a function to be called by exits. It returns
    zero if it failed, nonzero otherwise. 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
    exits. 
    
    
    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. 
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 SOURCE     
 SEE ALSO     
 BUGS     
 |  |  |  | Because of limitations of Unix, the exit status of a process can
    only be an 8-bit integer. Exits and _exits treat null or empty
    exit status as exit code 0 and call 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 implementations
    of exitcode . 
    
    
    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, atexit and
    atexitdont are preprocessor macros defined as p9atexit and p9atexitdont;
    see intro(3). 
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