1ALIAS(1P) POSIX Programmer's Manual ALIAS(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 alias — define or display aliases
13
15 alias [alias-name[=string]...]
16
18 The alias utility shall create or redefine alias definitions or write
19 the values of existing alias definitions to standard output. An alias
20 definition provides a string value that shall replace a command name
21 when it is encountered; see Section 2.3.1, Alias Substitution.
22 An alias definition shall affect the current shell execution environ‐
24 ment and the execution environments of the subshells of the current
25 shell. When used as specified by this volume of POSIX.1‐2017, the alias
26 definition shall not affect the parent process of the current shell nor
27 any utility environment invoked by the shell; see Section 2.12, Shell
28 Execution Environment.
29
31 None.
32
34 The following operands shall be supported:
35 alias-name
37 Write the alias definition to standard output.
38 alias-name=string
40 Assign the value of string to the alias alias-name.
41 If no operands are given, all alias definitions shall be written to
43 standard output.
44
46 Not used.
47
49 None.
50
52 The following environment variables shall affect the execution of
53 alias:
54 LANG Provide a default value for the internationalization vari‐
56 ables that are unset or null. (See the Base Definitions vol‐
57 ume of POSIX.1‐2017, Section 8.2, Internationalization Vari‐
58 ables for the precedence of internationalization variables
59 used to determine the values of locale categories.)
60 LC_ALL If set to a non-empty string value, override the values of
62 all the other internationalization variables.
63 LC_CTYPE Determine the locale for the interpretation of sequences of
65 bytes of text data as characters (for example, single-byte as
66 opposed to multi-byte characters in arguments).
67 LC_MESSAGES
69 Determine the locale that should be used to affect the format
70 and contents of diagnostic messages written to standard
71 error.
72 NLSPATH Determine the location of message catalogs for the processing
74 of LC_MESSAGES.
75
77 Default.
78
80 The format for displaying aliases (when no operands or only name oper‐
81 ands are specified) shall be:
82 "%s=%s\n", name, value
85 The value string shall be written with appropriate quoting so that it
87 is suitable for reinput to the shell. See the description of shell
88 quoting in Section 2.2, Quoting.
89
91 The standard error shall be used only for diagnostic messages.
92
94 None.
95
97 None.
98
100 The following exit values shall be returned:
101 0 Successful completion.
103 >0 One of the name operands specified did not have an alias defini‐
105 tion, or an error occurred.
106
108 Default.
109 The following sections are informative.
111
113 None.
114
116 1. Create a short alias for a commonly used ls command:
117 alias lf="ls -CF"
120 2. Create a simple ``redo'' command to repeat previous entries in the
122 command history file:
123 alias r='fc -s'
126 3. Use 1K units for du:
128 alias du=du\ -k
131 4. Set up nohup so that it can deal with an argument that is itself an
133 alias name:
134 alias nohup="nohup "
137
139 The alias description is based on historical KornShell implementations.
140 Known differences exist between that and the C shell. The KornShell
141 version was adopted to be consistent with all the other KornShell fea‐
142 tures in this volume of POSIX.1‐2017, such as command line editing.
143 Since alias affects the current shell execution environment, it is gen‐
145 erally provided as a shell regular built-in.
146 Historical versions of the KornShell have allowed aliases to be
148 exported to scripts that are invoked by the same shell. This is trig‐
149 gered by the alias -x flag; it is allowed by this volume of
150 POSIX.1‐2017 only when an explicit extension such as -x is used. The
151 standard developers considered that aliases were of use primarily to
152 interactive users and that they should normally not affect shell
153 scripts called by those users; functions are available to such scripts.
154 Historical versions of the KornShell had not written aliases in a
156 quoted manner suitable for reentry to the shell, but this volume of
157 POSIX.1‐2017 has made this a requirement for all similar output. There‐
158 fore, consistency was chosen over this detail of historical practice.
159
161 None.
162
164 Section 2.9.5, Function Definition Command
165 The Base Definitions volume of POSIX.1‐2017, Chapter 8, Environment
167 Variables
168
170 Portions of this text are reprinted and reproduced in electronic form
171 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
172 table Operating System Interface (POSIX), The Open Group Base Specifi‐
173 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
174 Electrical and Electronics Engineers, Inc and The Open Group. In the
175 event of any discrepancy between this version and the original IEEE and
176 The Open Group Standard, the original IEEE and The Open Group Standard
177 is the referee document. The original Standard can be obtained online
178 at http://www.opengroup.org/unix/online.html .
179 Any typographical or formatting errors that appear in this page are
181 most likely to have been introduced during the conversion of the source
182 files to man page format. To report such errors, see https://www.ker‐
183 nel.org/doc/man-pages/reporting_bugs.html .
184IEEE/The Open Group 2017 ALIAS(1P)