The local builtin command¶
Synopsis¶
local [option] name[=value] ...
Description¶
local
is identical to declare in every way, and takes all the same options, with 3 exceptions:
- Usage outside of a function is an error. Both
declare
andlocal
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 asdeclare
with no options, except the variables are filtered to print only locals that were set in the same scope from whichlocal
was called. Variables in parent scopes are not printed.- If name is '-', the set of shell options is made local to the function in which local is invoked: shell options changed using the set builtin inside the function are restored to their original values when the function returns. The restore is effected as if a series of set commands were executed to restore the values that were in place before the function.
Portability considerations¶
-
local
is not specified by POSIX. Most bourne-like shells don't have a builtin calledlocal
, but some such asdash
and the busybox shell do. -
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. -
In ksh93, using POSIX-style function definitions,
typeset
doesn't setlocal
variables, but rather acts upon variables of the next-outermost scope (e.g. setting attributes). Usingtypeset
within functions defined using kshfunction name {
syntax, variables follow roughly lexical-scoping, 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 throughnamerefs
.