Can one declare multiple local variables in one line

Question

Say one have a function/method foo. Can one use the local keyword to declare multiple variables in one line, or do they have to be separated by one declare statement for each variable?

foo()
{
    local x y z
}

or

foo()
{
    local x
    local y
    local z
}

And further:

foo()
{
    local -i x -a y  z
}

foo()
{
    local -i x=2 -a y=()  z
}

…

or the equivalent one by one line declaration.

---

Yes. Could test, but for one I can not find any Q/A on this, and second – there might be some hidden caveats 😏

Answer 1

Yes you can. A possible caveat is SC2155 in that you should declare and assign separately.

That being said it will work except for using multiple declare options between the parameters. Also note that the declare parameters will apply to all variables (in this case -i).

script0:

#!/bin/bash

declare a b c
a=foo
b=bar
c=baz

foo () {
    local a=1 b=2 c=3

    echo "From within func:"
    declare -p a
    declare -p b
    declare -p c
}

foo

echo "From outside func:"
declare -p a
declare -p b
declare -p c

Output:

$ ./script.sh
From within func:
declare -- a="1"
declare -- b="2"
declare -- c="3"
From outside func:
declare -- a="foo"
declare -- b="bar"
declare -- c="baz"

---

script1:

#!/usr/bin/env bash

declare -i a -a b c
a=foo
b=(bar)
c=baz

foo () {
    local -i a=1 -a b=(2) c=3

    echo "From within func:"
    declare -p a
    declare -p b
    declare -p c
}

foo

echo "From outside func:"
declare -p a
declare -p b
declare -p c

Output:

$ ./script.sh
./script.sh: line 3: declare: `-a': not a valid identifier
./script.sh: line 9: local: `-a': not a valid identifier
From within func:
declare -i a="1"
declare -ai b=([0]="2")
declare -i c="3"
From outside func:
declare -i a="0"
declare -ai b=([0]="0")
declare -i c="0"

Answer 2

To add to @jesse_b's excellent answer. I can confirm this also works (and takes into account the best practise of SC2155):

foo()
{
  local x y z
  x=1
  y=2
  z=3
}