What does ';;' mean?

Question

What does the meaning of ;; in this code from ~/bashrc file?

case $- in
    *i*) ;;
      *) return;;
esac

Can I use ;; in other ways? and where?

Answer 1

From man bash:

          If the ;; operator is used, no subsequent matches are
          attempted after the first pattern match.  Using ;& in  place  of
          ;;  causes  execution  to continue with the list associated with
          the next set of patterns.  Using ;;& in place of ;;  causes  the
          shell  to  test  the next pattern list in the statement, if any,
          and execute any associated list on a successful match.

So no, you can't use ";;" elsewhere, it's case-specific syntax in bash scripts. As for the meaning, if you finish each case item with ;;, it will stop after executing the code for the first match. If you use ;& instead, it will execute the first match, then continue looking for other matches, so you could perform multiple match actions.

For additional information see

http://linuxcommand.org/

and

http://www.tldp.org/LDP/Bash-Beginners-Guide/html/

Answer 2

That is the end of a single item in your case-switch,
see e.g.: bash-case-statement

Answer 3

The double semicolon indicates the end of the case branch. See help case command for details.