On Mon, Oct 10, 2011 at 08:06:17PM +0200, Peter Schreiber wrote: > 3.1.17(1)-release: > > -> [[ a =~ a|b ]] && echo true > -bash: syntax error in conditional expression: unexpected token `|' > > -> [[ a =~ a\|b ]] && echo true # that one works in version 3 > true > > =================================================================== > > 4.1.10(4)-release: > > -> [[ a =~ a\|b ]] && echo true # ... but not in version 4 > > -> [[ a =~ a|b ]] && echo true > true > > > Do I really need to check BASH_VERSION first?
Always store the regular expression that you intend to use on the right hand side of =~ in a variable. re='a|b' if [[ $a =~ $re ]]; then ... That is the only way to be sure it will work in whatever version of bash you happen to be using.
