xref: /freebsd/lib/libc/stdlib/exit.3 (revision 22cf89c938886d14f5796fc49f9f020c23ea8eaf)
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32.\"     @(#)exit.3	8.1 (Berkeley) 6/4/93
33.\"
34.Dd August 5, 2021
35.Dt EXIT 3
36.Os
37.Sh NAME
38.Nm exit , _Exit
39.Nd perform normal program termination
40.Sh LIBRARY
41.Lb libc
42.Sh SYNOPSIS
43.In stdlib.h
44.Ft void
45.Fn exit "int status"
46.Ft void
47.Fn _Exit "int status"
48.Sh DESCRIPTION
49The
50.Fn exit
51and
52.Fn _Exit
53functions terminate a process.
54.Pp
55Before termination,
56.Fn exit
57performs the following functions in the order listed:
58.Bl -enum -offset indent
59.It
60Call all functions registered with the
61.Xr __cxa_atexit 3
62function
63(which are typically destructors from the loaded dynamic objects),
64and the functions registered with the
65.Xr atexit 3
66function, in the reverse order of their registration.
67.It
68Flush all open output streams.
69.It
70Close all open streams.
71.El
72.Pp
73The
74.Fn _Exit
75function terminates without calling the functions registered with the
76.Xr atexit 3
77function, and may or may not perform the other actions listed.
78The
79.Fx
80implementation of the
81.Fn _Exit
82function does not call destructors registered with
83.Xr __cxa_atexit 3,
84does not flush buffers, and does not close streams.
85.Pp
86Both functions make the low-order eight bits of the
87.Fa status
88argument available to a parent process which has called a
89.Xr wait 2 Ns -family
90function.
91.Pp
92The C Standard
93.Pq St -isoC-99
94defines the values
95.Li 0 ,
96.Dv EXIT_SUCCESS ,
97and
98.Dv EXIT_FAILURE
99as possible values of
100.Fa status .
101Cooperating processes may use other values;
102in a program which might be called by a mail transfer agent, the
103values described in
104.Xr sysexits 3
105may be used to provide more information to the parent process.
106.Pp
107Note that
108.Fn exit
109does nothing to prevent bottomless recursion should a function registered
110using
111.Xr atexit 3
112itself call
113.Fn exit .
114Such functions must call
115.Fn _Exit
116instead (although this has other effects as well which may not be desired).
117.Sh RETURN VALUES
118The
119.Fn exit
120and
121.Fn _Exit
122functions
123never return.
124.Sh SEE ALSO
125.Xr _exit 2 ,
126.Xr abort2 2 ,
127.Xr wait 2 ,
128.Xr at_quick_exit 3 ,
129.Xr atexit 3 ,
130.Xr intro 3 ,
131.Xr quick_exit 3 ,
132.Xr sysexits 3 ,
133.Xr tmpfile 3
134.Sh STANDARDS
135The
136.Fn exit
137and
138.Fn _Exit
139functions conform to
140.St -isoC-99 .
141.Sh HISTORY
142The
143.Fn exit
144function appeared in
145.At v1 .
146