Regex in KornShell

Question

I am trying to check whether a variable is exactly two numbers but I can not seem to figure it out.

How do you do check regular expressions (regex) in KornShell (ksh

Answer 1

you can try this as well

$ month=100
$ [[ $month == {1,2}([0-9]) ]] && echo "ok" || echo "no"
no
$ [[ $month == [0-9][0-9] ]] && echo "ok" || echo "no"
no
$ month=10
$ [[ $month == {1,2}([0-9]) ]] && echo "ok" || echo "no"
ok
$ [[ $month == [0-9][0-9] ]] && echo "ok" || echo "no"
ok