New to regex, need help

aiman · 08-25-2011, 02:30 PM

Hi guys am new to regex and am stuck, I need to extract text between first hyphen and first .(dot) from my hostname which is of the type

abcdqa-asd-sd.local

I want to get asd-sd through regex, the pattern of hostname always remains the same as stated.

Please help
Thanks

AlucardZero · 08-25-2011, 03:00 PM

Useful site: http://www.regular-expressions.info/

You should mention where you are using regexes for the best help. Basic REs are less than Extended REs are less than Perl Compatible REs.

Assuming you're using Perl you want

Code:

$string =~ /-(.+)\./;
print "$1\n";

Pretty simple regex.

Tinkster · 08-25-2011, 04:00 PM

Or with sed

Code:

echo abcdqa-asd-sd.local | sed -r 's/^[^-]+-([^.]+).*/\1/'
asd-sd

PTrenholme · 08-25-2011, 05:52 PM

Code:

$ echo abcdqa-asd-sd.local | gawk '{$0=gensub(/^[^-]+-([^.]+).*/,"\\1","n");print}'
asd-sd

And your could do gawk '{$0=gensub(/^[^-]+-([^.]+).*/,"\\1","n");print}' <input> > <output> to process a file. (Lines that don't match the expression would be copied verbatim to the output.)

kurumi · 08-25-2011, 11:21 PM

If you have Ruby(1.9+) or any language that supports splitting strings with limits.

Code:

string="abcdqa-asd-sd.local"
puts string.split("-",2)[-1].split(".")[0]

No regex needed. First split the string on "-". The parameter "2" means split on 2 fields. Then split on the last field ( the text you want is somewhere there) on "." and get the first element.

Or else, you can do it with bash

Code:

$ string="abcdqa-asd-sd.local"
$ echo ${string#*-}
asd-sd.local
$ string=${string#*-}
$ echo ${string%%.*}
asd-sd

grail · 08-26-2011, 12:15 AM

Awk alternative:

Code:

echo "abcdqa-asd-sd.local" | awk -F"[-.]" '{print $2,$3}' OFS="-"

kurumi · 08-26-2011, 12:24 AM

Quote:

Originally Posted by grail

Awk alternative:

Code:

echo "abcdqa-asd-sd.local" | awk -F"[-.]" '{print $2,$3}' OFS="-"

Nice. But may not work if there are multiple hyphens.....

David the H. · 08-26-2011, 01:45 AM

In bash, using full regex:

Code:

string="abcdqa-asd-sd.local"
re='^[^-]+-([^.]+)\.'

[[ "$string" =~ $re ]]

echo "${BASH_REMATCH[1]}"

grail · 08-26-2011, 02:01 AM

Quote:

Nice. But may not work if there are multiple hyphens

True enough, but simple change:

Code:

echo "abcdqa-asd-sd.local" | awk -F"[-.]" '{print $2,$(NF-1)}' OFS="-"

kurumi · 08-26-2011, 04:17 AM

Quote:

Originally Posted by grail

True enough, but simple change:

Code:

echo "abcdqa-asd-sd.local" | awk -F"[-.]" '{print $2,$(NF-1)}' OFS="-"

nice, but again, it will not work if there is string like "abcdqa-asd---jgsd.local". (of course, I am being picky here

)

kurumi · 08-26-2011, 04:22 AM

Quote:

Originally Posted by David the H.

In bash, using full regex:

Code:

string="abcdqa-asd-sd.local"
re='^[^-]+-([^.]+)\.'

[[ "$string" =~ $re ]]

echo "${BASH_REMATCH[1]}"

nice, but that won't work with strings like "-abcdqa-asd---jgsd.local" (yes, I am being picky

)

grail · 08-26-2011, 06:28 AM

Quote:

nice, but again, it will not work if there is string like "abcdqa-asd---jgsd.local". (of course, I am being picky here )

Please pick away as I always like a challenge

Code:

echo "abcdqa-asd---jgsd.local" | awk -F. '{print gensub(/[^-]*-/,"","1",$1)}'