Question

I want make a bash script which returns the position of an element from an array by give an arg. See code below, I use:

#!/bin/bash
args=("$@")
echo ${args[0]}
test_array=('AA' 'BB' 'CC' 'DD' 'EE')
echo $test_array
elem_array=${#test_array[@]}
for args in $test_array
do
        echo 
done

Finally I should have output like:

$script.sh DD
4

Answer 1

Trying to avoid complex tools:

test_array=('AA' 'BB' 'CC' 'D D' 'EE')
OLD_IFS="$IFS"
IFS="
"
element=$(grep -n '^D D$' <<< "${test_array[*]}" | cut -d ":" -f 1)
IFS="$OLD_IFS"
echo $element

However, it consumes 2 processes. If we allow ourselves sed, we could do it with a single process:

test_array=('AA' 'BB' 'CC' 'D D' 'EE')
OLD_IFS="$IFS"
IFS="
"
element=$(sed -n -e '/^D D$/=' <<< "${test_array[*]}")
IFS="$OLD_IFS"
echo $element

Update:

As pointed out by thkala in the comments, this solution is broken in 3 cases. Be careful not to use it if:

1. You want zero indexed offset.
2. You have newlines in your array elements.
3. And you have a sparse array, or have other keys than integers.