How to get a substring after the last underscore (_) in unix shell script

Question

I have a String like this

this_is_test_string1_22
this_is_also_test_string12_6

I wanted to split and extracts string around the last unders

Answer 1

You can do

s='this_is_test_string1_22'

In BASH:

echo "${s##*_}"
22

OR using sed:

sed 's/^.*_\([^_]*\)$/\1/' <<< 'this_is_test_string1_22'
22

EDIT for sh:

echo "$s" | sed 's/^.*_\([^_]*\)$/\1/'