wiki.bash-hackers.org/commands/builtin/local.md

# The local builtin command

## Synopsis

    local [option] name[=value] ...

## Description

`local` is identical to [declare](/commands/builtin/declare.md) in every
way, and takes all the same options, with two exceptions:

- Usage outside of a function is an error. Both `declare` and `local`
  within a function have the same effect on variable scope, including
  the -g option.
- `local` with no options prints variable names and values in the same
  format as `declare` with no options, except the variables are filtered
  to print only locals that were set in the same scope from which
  `local` was called. Variables in parent scopes are not printed.

## Portability considerations

- `local` is not specified by POSIX. Most bourne-like shells don't have
  a builtin called `local`, but some such as `dash` and the busybox
  shell do.

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- The behavior of function scope is not defined by POSIX, however local
  variables are implemented widely by bourne-like shells, and behavior
  differs substantially. Even the`dash` shell has local variables.

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- In ksh93, using POSIX-style function definitions, `typeset` doesn't
  set `local` variables, but rather acts upon variables of the
  next-outermost scope (e.g. setting attributes). Using `typeset` within
  functions defined using ksh `function name {` syntax, variables follow
  roughly
  [lexical-scoping](http://community.schemewiki.org/?lexical-scope),
  except that functions themselves don't have scope, just like Bash.
  This means that even functions defined within a "function's scope"
  don't have access to non-local variables except through `namerefs`.

## See also