As a `grep -q` user I can confirm that modern Solarises and osx also support it. On Wed, May 28, 2014 at 11:19 PM, der.hans wrote: > Am 28. Mai, 2014 schwätzte Bryan O'Neal so: > > moin moin Bryan, > > because you're weird :). Or maybe that's Al, > http://www.youtube.com/watch?v=JUQDzj6R3p4 :). > > Not every grep supports -q, but I don't know if that's the case for > current releases. GNU grep has supported it for years and years. Looks > like FreeBSD has for at least a few major releases, so also for years and > years. > > AIX, Solaris, etc. probably don't, but you should install GNU grep, GNU > date, etc. on those anyway :). > > [[ ]] vs [ ] is just for extra emphasis :). Or maybe... [[ ]] is for > compound commands and [ ] is for test. Both use conditional expressions. > > The compound command, [[ ]], allows extra operators. > > == and != allow glob pattern matching: > > $ ( fred=anke; if [[ $fred == *ke ]] ; then echo $fred; fi ) > anke > $ > > $ ( fred=anke; if [ $fred == *ke ] ; then echo $fred; fi ) > $ > > $ ( fred=anke; if [[ $fred == [:alpha:]?ke ]] ; then echo $fred; fi ) > anke > $ > > =~ allows regex pattern matching: > > $ ( fred=anke; if [[ $fred == [:alpha:]*ke ]] ; then echo $fred; fi ) > anke > $ > > Hmm, cool. According to bash(1), "If the regular expression is > syntactically incorrect, the conditional expression's return value is 2." > > Note that the patterns to be matched must be on the right hand side of the > operator. > > Now I need to make time to update my class materials as I just realized > there's a dearth of references to Weird Al :). > > ciao, > > der.hans > > > So I had a coworker ask me why I always do >> echo $foo | grep $bar > /dev/null >> if [[ $? -eq 0]] then; .... >> >> Instead of just using greps quiet option. And I remember their being >> some definite bug with -q and checking return codes but for the life >> of me I can not recall it right now. Just like I can not recall why I >> use [[ ]] insted of just [ ]. Their was a reason I switched at some >> point but can not recall what it is. >> It could have been somthing with egrep or using peal regex with grep >> but honestly I can not recall... >> >> Thus I am here to ask you, my fellow bash geeks, what what that reason! >> --------------------------------------------------- >> PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org >> To subscribe, unsubscribe, or to change your mail settings: >> http://lists.phxlinux.org/mailman/listinfo/plug-discuss >> >> > -- > # http://www.LuftHans.com/ http://www.LuftHans.com/Classes/ > # "It's not that I'm so smart, it's just that I stay with problems > longer." > # -- Albert Einstein > --------------------------------------------------- > PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org > To subscribe, unsubscribe, or to change your mail settings: > http://lists.phxlinux.org/mailman/listinfo/plug-discuss > -- Paul Mooring Operations Engineer Chef