1EXIT(1P) POSIX Programmer's Manual EXIT(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 exit — cause the shell to exit
13
15 exit [n]
16
18 The exit utility shall cause the shell to exit from its current execu‐
19 tion environment with the exit status specified by the unsigned decimal
20 integer n. If the current execution environment is a subshell environ‐
21 ment, the shell shall exit from the subshell environment with the spec‐
22 ified exit status and continue in the environment from which that sub‐
23 shell environment was invoked; otherwise, the shell utility shall ter‐
24 minate with the specified exit status. If n is specified, but its value
25 is not between 0 and 255 inclusively, the exit status is undefined.
26 A trap on EXIT shall be executed before the shell terminates, except
28 when the exit utility is invoked in that trap itself, in which case the
29 shell shall exit immediately.
30
32 None.
33
35 See the DESCRIPTION.
36
38 Not used.
39
41 None.
42
44 None.
45
47 Default.
48
50 Not used.
51
53 The standard error shall be used only for diagnostic messages.
54
56 None.
57
59 None.
60
62 The exit status shall be n, if specified, except that the behavior is
63 unspecified if n is not an unsigned decimal integer or is greater than
64 255. Otherwise, the value shall be the exit value of the last command
65 executed, or zero if no command was executed. When exit is executed in
66 a trap action, the last command is considered to be the command that
67 executed immediately preceding the trap action.
68
70 Default.
71 The following sections are informative.
73
75 None.
76
78 Exit with a true value:
79 exit 0
82 Exit with a false value:
84 exit 1
87 Propagate error handling from within a subshell:
89 (
92 command1 || exit 1
93 command2 || exit 1
94 exec command3
95 ) > outputfile || exit 1
96 echo "outputfile created successfully"
97
99 As explained in other sections, certain exit status values have been
100 reserved for special uses and should be used by applications only for
101 those purposes:
102 126 A file to be executed was found, but it was not an executable
104 utility.
105 127 A utility to be executed was not found.
107 >128 A command was interrupted by a signal.
109 The behavior of exit when given an invalid argument or unknown option
111 is unspecified, because of differing practices in the various histori‐
112 cal implementations. A value larger than 255 might be truncated by the
113 shell, and be unavailable even to a parent process that uses waitid()
114 to get the full exit value. It is recommended that implementations that
115 detect any usage error should cause a non-zero exit status (or, if the
116 shell is interactive and the error does not cause the shell to abort,
117 store a non-zero value in "$?"), but even this was not done histori‐
118 cally in all shells.
119
121 None.
122
124 Section 2.14, Special Built-In Utilities
125
127 Portions of this text are reprinted and reproduced in electronic form
128 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
129 table Operating System Interface (POSIX), The Open Group Base Specifi‐
130 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
131 Electrical and Electronics Engineers, Inc and The Open Group. In the
132 event of any discrepancy between this version and the original IEEE and
133 The Open Group Standard, the original IEEE and The Open Group Standard
134 is the referee document. The original Standard can be obtained online
135 at http://www.opengroup.org/unix/online.html .
136 Any typographical or formatting errors that appear in this page are
138 most likely to have been introduced during the conversion of the source
139 files to man page format. To report such errors, see https://www.ker‐
140 nel.org/doc/man-pages/reporting_bugs.html .
141IEEE/The Open Group 2017 EXIT(1P)