Question

I have successfully made a join function, which joins an array to a string using the delimeter:

function join() # Usage: string=$(join "delimeter" "${array[@]}" )
{
    local array=( "${@:2}" )
    OLD_IFS="$IFS"
    IFS="$1"
    local string="${array[*]}"
    IFS="$OLD_IFS"
    echo "$string"
}

I have also tried to make a split function which should do the opposite:

function split() # Usage: array=( $(split "delimeter" "$string") )
{
    OLD_IFS="$IFS"
    IFS="$1"
    local array=( $2 )
    IFS="$OLD_IFS"
    echo "${array[@]}"
}

But, when I use the split command and the result contains spaces, it will not work as expected.
Example:

array=( "foo" "bar" "baz" "foo bar" )
string=$(join "|" "${array[@]}")
echo $string
array=( $(split "|" "$string") )
for i in ${array[@]}
do
    echo $i
done

The last element “foo bar” has been split too.
I think the solution is that you have to do array=( "$(split '|' "$string")" ), but I do not know how to nest the quotes probably.

Answer 1

Note that IFS can be a local variable in a function, so you don’t have to backup and restore its value:

join () { local IFS="$1"; local s="${@:2}"; printf "%s" "$s"; }

Here’s an implementation of split that requires an eval:

# usage: split varName separator stringToSplit
split () {
  local var="$1"
  local IFS="$2"
  set -- $3
  echo "declare -a $var=( $(printf "\"%s\" " "$@") )"
}

Demonstration

$ a=( foo bar "hello world" baz )
$ s=$(join , "${a[@]}")
$ echo $s
foo,bar,hello world,baz
$ split b , "$s"
declare -a b=( "foo" "bar" "hello world" "baz"  )
$ eval $(split b , "$s")
$ for x in "${b[@]}"; do echo "$x"; done
foo
bar
hello world
baz