local

Additional Notes

local is a Bash shell built-in that declares a variable with local scope inside a function. Variables declared with local are visible only within that function and any functions it calls; they do not affect variables of the same name in the caller scope.

Using local prevents accidental variable name collisions and side effects between functions. It is considered a best practice to use local for all variables inside shell functions.

Syntax

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

Parameters

• name: The variable name to declare as local.
• =value: Optional initial value assignment.

Common Options

• -a: Declare the variable as an indexed array.
• -A: Declare the variable as an associative array.
• -i: Declare the variable as an integer.
• -l: Declare the variable in lowercase (Bash 4+).
• -u: Declare the variable in uppercase (Bash 4+).
• -r: Declare the variable as read-only.
• -x: Export the local variable to child processes.

Examples

myfunc() {
  local count=0
  local name
  name="Alice"
  echo "$count $name"
}

Declare and use local variables inside a function.

myfunc() {
  local -i total=0
  for i in {1..5}; do
    total+=i
  done
  echo $total
}

Use local integer arithmetic.

myfunc() {
  local -a fruits=("apple" "banana" "cherry")
  echo "${fruits[1]}"
}

Declare a local indexed array.

myfunc() {
  local -A capitals=(["France"]="Paris" ["Japan"]="Tokyo")
  echo "${capitals[France]}"
}

Declare a local associative array.

Practical Notes

• Always use local for variables inside functions to avoid polluting the global namespace.
• local can only be used inside a function; using it outside a function causes an error.
• The typeset command is a synonym for local in many shells but local is preferred for clarity.
• In POSIX sh, local is not standard; use it only in Bash, Zsh, or Ksh.