Anchor(faq66)

I want to check if [[ $var == foo || $var == bar || $var == more ]] without repeating $var n times.

Here's a portable solution: 

   case $var in
      foo|bar|more) ... ;;
   esac

And here's one that uses '[[': 

   if [[ $var =~ foo|bar|more ]]; then
      ...
   fi