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In [[BASH]]:
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{{{case}}} allows you to match variables against [[globbing]]-style patterns. If you need a portable way to match variables against [[RegularExpression|regular expressions]], use {{{grep}}} or {{{egrep}}}. {{{case}}} allows you to match variables against [[glob|globbing]]-style patterns (including extended globs, if your shell offers them). If you need a portable way to match variables against [[RegularExpression|regular expressions]], use {{{grep}}} or {{{egrep}}}.

How do I determine whether a variable contains a substring?

In BASH:

  if [[ $foo = *bar* ]]

The above works in virtually all versions of Bash. Bash version 3 also allows regular expressions:

  if [[ $foo =~ ab*c ]]   # bash 3, matches abbbbcde, or ac, etc.

If you are programming in the BourneShell instead of Bash, there is a more portable (but less pretty) syntax:

  case "$foo" in
    *bar*) .... ;;
  esac

case allows you to match variables against globbing-style patterns (including extended globs, if your shell offers them). If you need a portable way to match variables against regular expressions, use grep or egrep.

  if echo "$foo" | grep bar >/dev/null; then ...

BashFAQ/041 (last edited 2013-07-24 15:34:17 by 188-223-3-27)