I need a one line program ;-)

Hi, I need a one liner program or similar short: I need to test a text file for a certain line and if this one is not exactly the match I have, than it should replace the line with the given one. If it is missing, than this line must be added. Can anybody help me to do that? Thanks! bye Ronald -- Ronald Wiplinger (CEO of ELMIT) http://www.elmit.com +886 (0) 915 653-452 - I'm a SpamCon Foundation Member, #694, Verify it at http://www.spamcon.org