Environment: CentOS 4.2 (RHES4 clone) Ruby 1.8.4 Rails 1.0 I am having a small difficulty with case sensitive matching in some ruby code: f_nam_re = Regexp.new(f_nam_re_s,"x") produces these test results: The passed regexp: ^QPCCCMR[[:digit:]]$ The regexp used is: /^QPCCCMR[[:digit:]]$/i $= is false qpcccmr1 matches QPCCCMR1 matches QPCCMMR1 does not match qpCCCMR1 matches QPCCCMRC does not match QPCCCMR1.csv does not match QPCCCMR9 matches XXQPCCCMR9 does not match QPCCCMR9yyy does not match XyZQPCCCMR3AbC does not match However, just removing the "x" f_nam_re = Regexp.new(f_nam_re_s) Produces this from the same test suite: The passed regexp: ^QPCCCMR[[:digit:]]$ The regexp used is: /^QPCCCMR[[:digit:]]$/ $= is false qpcccmr1 does not match QPCCCMR1 matches QPCCMMR1 does not match qpCCCMR1 does not match QPCCCMRC does not match QPCCCMR1.csv does not match QPCCCMR9 matches XXQPCCCMR9 does not match QPCCCMR9yyy does not match XyZQPCCCMR3AbC does not match So, why does enabling regexp extensions force case insensitivity? Further, once it is turned on in this fashion I cannot seem to get it switched off even when using the (?-i:) construct. I would very much appreciate a direct copy of any reply to the list as I subscribe to the digest version of. Regards, Jim -- *** e-mail is not a secure channel *** mailto:byrnejb.<token>@harte-lyne.ca James B. Byrne Harte & Lyne Limited vox: +1 905 561 1241 9 Brockley Drive fax: +1 905 561 0757 Hamilton, Ontario <token> = hal Canada L8E 3C3