xref: /freebsd/lib/libc/stdlib/exit.3 (revision c98323078dede7579020518ec84cdcb478e5c142)
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36.\"     @(#)exit.3	8.1 (Berkeley) 6/4/93
37.\" $FreeBSD$
38.\"
39.Dd September 9, 2002
40.Dt EXIT 3
41.Os
42.Sh NAME
43.Nm exit , _Exit
44.Nd perform normal program termination
45.Sh LIBRARY
46.Lb libc
47.Sh SYNOPSIS
48.In stdlib.h
49.Ft void
50.Fn exit "int status"
51.Ft void
52.Fn _Exit "int status"
53.Sh DESCRIPTION
54The
55.Fn exit
56and
57.Fn _Exit
58functions terminate a process.
59.Pp
60Before termination,
61.Fn exit
62performs the following functions in the order listed:
63.Bl -enum -offset indent
64.It
65Call the functions registered with the
66.Xr atexit 3
67function, in the reverse order of their registration.
68.It
69Flush all open output streams.
70.It
71Close all open streams.
72.It
73Unlink all files created with the
74.Xr tmpfile 3
75function.
76.El
77.Pp
78The
79.Fn _Exit
80function terminates without calling the functions registered with the
81.Xr atexit 3
82function, and may or may not perform the other actions listed.
83Both functions make the low-order eight bits of the
84.Fa status
85argument available to a parent process which has called a
86.Xr wait 2 Ns -family
87function.
88.Pp
89The C Standard
90.Pq St -isoC-99
91defines the values
92.Li 0 ,
93.Dv EXIT_SUCCESS ,
94and
95.Dv EXIT_FAILURE
96as possible values of
97.Fa status .
98Cooperating processes may use other values;
99in a program which might be called by a mail transfer agent, the
100values described in
101.Xr sysexits 3
102may be used to provide more information to the parent process.
103.Pp
104Note that
105.Fn exit
106does nothing to prevent bottomless recursion should a function registered
107using
108.Xr atexit 3
109itself call
110.Fn exit .
111Such functions must call
112.Fn _Exit
113instead (although this has other effects as well which may not be desired).
114.Sh RETURN VALUES
115The
116.Fn exit
117and
118.Fn _Exit
119functions
120never return.
121.Sh SEE ALSO
122.Xr _exit 2 ,
123.Xr wait 2 ,
124.Xr atexit 3 ,
125.Xr intro 3 ,
126.Xr sysexits 3 ,
127.Xr tmpfile 3
128.Sh STANDARDS
129The
130.Fn exit
131and
132.Fn _Exit
133functions conform to
134.St -isoC-99 .
135