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@(#)atexit.3 8.1 (Berkeley) 6/4/93
$FreeBSD$
.Dd September 6, 2002 .Dt ATEXIT 3 .Os .Sh NAME .Nm atexit .Nd register a function to be called on exit .Sh LIBRARY .Lb libc .Sh SYNOPSIS n stdlib.h .Ft int .Fn atexit "void (*function)(void)" .Ft int .Fn atexit_b "void (^function)(void)" .Sh DESCRIPTION The .Fn atexit function registers the given .Fa function to be called at program exit, whether via .Xr exit 3 or via return from the program's .Fn main . Functions so registered are called in reverse order; no arguments are passed.
p These functions must not call .Fn exit ; if it should be necessary to terminate the process while in such a function, the .Xr _exit 2 function should be used. (Alternatively, the function may cause abnormal process termination, for example by calling .Xr abort 3 . )
p At least 32 functions can always be registered, and more are allowed as long as sufficient memory can be allocated.
p
The
.Fn atexit_b
function behaves identically to
.Fn atexit ,
except that it takes a block, rather than a function pointer.
XXX {ATEXIT_MAX} is not implemented yet
.Sh RETURN VALUES
.Rv -std atexit
.Sh ERRORS
l -tag -width Er t Bq Er ENOMEM No memory was available to add the function to the list.
The existing list of functions is unmodified.
t Bq Er ENOSYS The
.Fn atexit_b
function was called by a program that did not supply a
.Fn _Block_copy
implementation.
.El
.Sh SEE ALSO
.Xr at_quick_exit 3 ,
.Xr exit 3
.Sh STANDARDS
The
.Fn atexit
function
conforms to
.St -isoC .