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Grep expression between double quotes

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Homework and Emergencies Emergency UNIX and Linux Support Grep expression between double quotes
# 8  
Old 12-22-2009
This one works perfectly i think
grep -o '"http://.*"' input_file
can anyone give a failing case?
# 9  
Old 12-22-2009
No that will only work if there is one address per line and if there are no further "-characters on that line. You may want to search for "greedy matching".
# 10  
Old 12-22-2009
Give more explanation, and some examples for good response....
# 11  
Old 12-22-2009
Sure:
Code:
$ echo '"http://a.b.c" blablabla "http://c.d.e"' |grep -o '"http://.*"'
"http://a.b.c" blablabla "http://c.d.e"

$ echo '"http://a.b.c" blablabla "http://c.d.e"' |grep -o '"http://[^"]*"'
"http://a.b.c"
"http://c.d.e"

$ echo '"http://a.b.c" blablabla ""' |grep -o '"http://.*"'
"http://a.b.c" blablabla ""

$ echo '"http://a.b.c" blablabla ""' |grep -o '"http://[^"]*"'
"http://a.b.c"

If you do not limit greedy matching grep will try to find the longest match possible, hence the use of [^"] instead of .
Last edited by Scrutinizer; 12-22-2009 at 12:47 PM..
# 12  
Old 12-23-2009
Quote:
Originally Posted by Scrutinizer
Sure:
Code:
$ echo '"http://a.b.c" blablabla "http://c.d.e"' |grep -o '"http://.*"'
"http://a.b.c" blablabla "http://c.d.e"

$ echo '"http://a.b.c" blablabla "http://c.d.e"' |grep -o '"http://[^"]*"'
"http://a.b.c"
"http://c.d.e"

$ echo '"http://a.b.c" blablabla ""' |grep -o '"http://.*"'
"http://a.b.c" blablabla ""

$ echo '"http://a.b.c" blablabla ""' |grep -o '"http://[^"]*"'
"http://a.b.c"

If you do not limit greedy matching grep will try to find the longest match possible, hence the use of [^"] instead of .
Scrutinizer you are wrong because see below:-
Iam using SunOS server2 5.10 Generic_118833-36 sun4u sparc SUNW,Netra-210

Code:
bash-3.00$ echo '"http://abc" blablabla "http://cvd"' | grep '"http://.*"'
o/p:- "http://abc" blablabla "http://cvd"

and when using the 2nd way:-

bash-3.00$ echo '"http://abc" blablabla "http://cvd"' | grep '"http://[^"]*"'

o/p:- "http://abc" blablabla "http://cvd"

both ways are acting greedy.
# 13  
Old 12-23-2009
Aaiaz, that is a peculiar conclusion given that I posted my output above that proved my point.

Besides: you left out the -o option! Without it you always print the entire line.
# 14  
Old 12-24-2009
-o option is not supported in grep command in my OS "SUN Solaries".
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