# Quick Regex Query **URL:** \ **Category:** Ruby\ **Created:** [December 23, 2005, 2:19pm UTC](https://www.ruby-forum.com/t/quick-regex-query/74450 "2005-12-23T14:19:11Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Neowulf](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/c4cdca/32.png) [@Neowulf](https://www.ruby-forum.com/u/Neowulf)\ **Post date:** [December 23, 2005, 2:19pm UTC](https://www.ruby-forum.com/t/quick-regex-query/74450/1 "2005-12-23T14:19:11Z")
Hi all, Really quick one for the regex gurus… Anyone know of a regex string which will extract out the stuff between “from” and “not” without the spaces between? User root from toronto-hs-216-138-233-211.s-ip.magma.ca not allowed because not listed in AllowUsers I’ve found something which _almost_ does the job… \bfrom\W+(?:\w+\W+){1,6}not\b This is limited however, as I can’t know for certain how many “words” will make up the hostname. I’ve got a non-regex solution already, but you don’t want to know how that one works… … something to do with using split and relying on the fact that the host name field always end up at the same index. Seems more than a little clunky. Any advise appreciated. Cheers ~Neowulf ---
**Author:** ![Neowulf](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/c4cdca/32.png) [@Neowulf](https://www.ruby-forum.com/u/Neowulf)\ **Post date:** [December 23, 2005, 2:55pm UTC](https://www.ruby-forum.com/t/quick-regex-query/74450/2 "2005-12-23T14:55:21Z")
Neowulf wrote: > I’ve found something which _almost_ does the job… > > \bfrom\W+(?:\w+\W+){1,6}not\b > > This is limited however, as I can’t know for certain how many “words” > will make up the hostname. why do the number of words matter? i thought you only needed the ‘stuff’ between ‘from’ and ‘not’. now when you say ‘without the spaces between’, do you mean the spaces immediately after the from, and before the not? what’s wrong with: /from\s+(\w+)\s+not/ && print “$1” # i’m more familiar with Perl, not sure if $1 works in # ruby, but it should contain what’s in capturing parens can you provide several examples of input and expected output that would illustrate your requirements? ---
**Author:** ![Neowulf](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/c4cdca/32.png) [@Neowulf](https://www.ruby-forum.com/u/Neowulf)\ **Post date:** [December 23, 2005, 4:04pm UTC](https://www.ruby-forum.com/t/quick-regex-query/74450/3 "2005-12-23T16:04:42Z")
Neowulf wrote: > I’ve found something which _almost_ does the job… > host name field always end up at the same index. > > Seems more than a little clunky. > > Any advise appreciated. > > Cheers > > ~Neowulf str = “User root from toronto-hs-216-138-233-211.s-ip.magma.ca not allowed because not listed in AllowUsers” m = /from (.\*?) not/.match(str) puts m[1] ---
**Author:** ![Neowulf](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/c4cdca/32.png) [@Neowulf](https://www.ruby-forum.com/u/Neowulf)\ **Post date:** [December 23, 2005, 5:50pm UTC](https://www.ruby-forum.com/t/quick-regex-query/74450/4 "2005-12-23T17:50:07Z")
Neowulf wrote: > I’ve found something which _almost_ does the job… > > \bfrom\W+(?:\w+\W+){1,6}not\b host\_name = /from\s+(\S+)\s+not/ =~ s && $1 > This is limited however, as I can’t know for certain how many “words” > will make up the hostname. But there won’t be any whitespace in the hostname, right? Then the RX above will do it. Kind regards ``` robert ``` ---
**Author:** ![Neowulf](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/c4cdca/32.png) [@Neowulf](https://www.ruby-forum.com/u/Neowulf)\ **Post date:** [December 24, 2005, 12:40am UTC](https://www.ruby-forum.com/t/quick-regex-query/74450/5 "2005-12-24T00:40:32Z")
Thanks Guys, Top effort all round. Regex gives me a serious head ache sometimes… Thanks again everyone for the help. ---
**Author:** ![Neowulf](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/c4cdca/32.png) [@Neowulf](https://www.ruby-forum.com/u/Neowulf)\ **Post date:** [December 23, 2005, 9:28pm UTC](https://www.ruby-forum.com/t/quick-regex-query/74450/6 "2005-12-23T21:28:03Z")
Robert K. wrote: > host\_name = /from\s+(\S+)\s+not/ =~ s && $1 Tsk, those Perl guys… 😉 host\_name[/from\s+(\S+)\s+not/, 1] # Will either return nil or a String ---
**Author:** ![Neowulf](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/c4cdca/32.png) [@Neowulf](https://www.ruby-forum.com/u/Neowulf)\ **Post date:** [December 27, 2005, 11:58am UTC](https://www.ruby-forum.com/t/quick-regex-query/74450/7 "2005-12-27T11:58:55Z")
Florian Groß [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Robert K. wrote: > > > host\_name = /from\s+(\S+)\s+not/ =~ s && $1 > > Tsk, those Perl guys… 😉 Ssshhh! I’m trying to get over my Perl heritage but sometimes it still haunts me… 🙂 > host\_name[/from\s+(\S+)\s+not/, 1] # Will either return nil or a > String Thanks for reminding me - I always keep forgetting this variant, especially with the group selector! Kind regards ``` robert ```