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58 lines
2.1 KiB
Markdown
58 lines
2.1 KiB
Markdown
# The local builtin command
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## Synopsis
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local [option] name[=value] ...
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## Description
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`local` is identical to [declare](/commands/builtin/declare) in every
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way, and takes all the same options, with 3 exceptions:
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- Usage outside of a function is an error. Both `declare` and `local`
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within a function have the same effect on variable scope, including
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the -g option.
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- `local` with no options prints variable names and values in the same
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format as `declare` with no options, except the variables are
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filtered to print only locals that were set in the same scope from
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which `local` was called. Variables in parent scopes are not
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printed.
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- If name is '-', the set of shell options is made local to the
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function in which local is invoked: shell options changed using the
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set builtin inside the function are restored to their original
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values when the function returns. The restore is effected as if a
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series of set commands were executed to restore the values that were
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in place before the function.
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## Portability considerations
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- `local` is not specified by POSIX. Most bourne-like shells don\'t
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have a builtin called `local`, but some such as `dash` and the
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busybox shell do.
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```{=html}
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<!-- -->
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```
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- The behavior of function scope is not defined by POSIX, however
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local variables are implemented widely by bourne-like shells, and
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behavior differs substantially. Even the`dash` shell has local
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variables.
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```{=html}
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<!-- -->
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```
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- In ksh93, using POSIX-style function definitions, `typeset` doesn\'t
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set `local` variables, but rather acts upon variables of the
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next-outermost scope (e.g. setting attributes). Using `typeset`
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within functions defined using ksh `function name {` syntax,
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variables follow roughly
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[lexical-scoping](http://community.schemewiki.org/?lexical-scope),
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except that functions themselves don\'t have scope, just like Bash.
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This means that even functions defined within a \"function\'s
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scope\" don\'t have access to non-local variables except through
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`namerefs`.
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## See also
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- <http://wiki.bash-hackers.org/scripting/basics#variable_scope>
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