|ALIAS(1P)||POSIX Programmer's Manual||ALIAS(1P)|
An alias definition shall affect the current shell execution environment and the execution environments of the subshells of the current shell. When used as specified by this volume of POSIX.1‐2017, the alias definition shall not affect the parent process of the current shell nor any utility environment invoked by the shell; see Section 2.12, Shell Execution Environment.
- Write the alias definition to standard output.
Assign the value of string to the alias alias-name.
If no operands are given, all alias definitions shall be written to standard output.
- Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of POSIX.1‐2017, Section 8.2, Internationalization Variables for the precedence of internationalization variables used to determine the values of locale categories.)
- If set to a non-empty string value, override the values of all the other internationalization variables.
- Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multi-byte characters in arguments).
Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.
- Determine the location of message catalogs for the processing of LC_MESSAGES.
"%s=%s\n", name, value
The value string shall be written with appropriate quoting so that it is suitable for reinput to the shell. See the description of shell quoting in Section 2.2, Quoting.
- Successful completion.
- One of the name operands specified did not have an alias definition, or an error occurred.
The following sections are informative.
- Create a short alias for a commonly used ls command:
alias lf="ls -CF"
- Create a simple ``redo'' command to repeat previous entries in the command history file:
alias r='fc -s'
- Use 1K units for du:
alias du=du\ -k
- Set up nohup so that it can deal with an argument that is itself an alias name:
alias nohup="nohup "
Since alias affects the current shell execution environment, it is generally provided as a shell regular built-in.
Historical versions of the KornShell have allowed aliases to be exported to scripts that are invoked by the same shell. This is triggered by the alias -x flag; it is allowed by this volume of POSIX.1‐2017 only when an explicit extension such as -x is used. The standard developers considered that aliases were of use primarily to interactive users and that they should normally not affect shell scripts called by those users; functions are available to such scripts.
Historical versions of the KornShell had not written aliases in a quoted manner suitable for reentry to the shell, but this volume of POSIX.1‐2017 has made this a requirement for all similar output. Therefore, consistency was chosen over this detail of historical practice.
The Base Definitions volume of POSIX.1‐2017, Chapter 8, Environment Variables
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|2017||IEEE/The Open Group|