using regular expression to extract subset from a line

ramthen has asked for the wisdom of the Perl Monks concerning the following question:

Seeking help on how to extract portion,

..\../system-build/ali/text/makefile

from the pattern given below

make -r -f ..\../tools/cell/makefile cell.lib

I tried regex given below, but did not work; could any one tell me what is wrong with this ?

/(.*)\s\.\.\\(.*)\/makefile/si

TIA

Then

Comment on using regular expression to extract subset from a line

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Re: using regular expression to extract subset from a line by DamnDirtyApe (Curate) on Dec 30, 2004 at 19:54 UTC
I'll leave the analysis of what you've got to someone who's better at regexps than I, but if you're simply looking to extract the argument from a space-delimited string that ends in "makefile", try something simpler like this: `#! /usr/bin/perl -w use strict; my $old_str = 'make -r -f ..\../tools/cell/makefile cell.lib'; my $new_str = ( $old_str =~ /\s+(\Smakefile)/ )[0]; print "New string: $new_str$/"; __END__` [download] HTH Update:* You could do this with `split` and `grep` also: `my $new_str = ( grep { /makefile$/ } split /\s+/, $old_str )[0];` [download] _______________ DamnDirtyApe Those who know that they are profound strive for clarity. Those who would like to seem profound to the crowd strive for obscurity. --Friedrich Nietzsche	[reply] [d/l] [select]
Re: using regular expression to extract subset from a line by Eimi Metamorphoumai (Deacon) on Dec 30, 2004 at 19:57 UTC
What exactly do you know about the part you want to extract? Here's a way that's similar to yours `/.\s(\.\.\\.\/makefile)/i;` [download] which will put the matched text in `$1`. But personally, I'd probably use something like `/-f\s*(\S+)/;` [download] to find whatever text is following the -f switch.	[reply] [d/l] [select]
Re: using regular expression to extract subset from a line by johnnywang (Priest) on Dec 30, 2004 at 20:21 UTC
It looks like you want everything after "-f" up to "makefile", how about the following: `use strict; while(<DATA>){ print m\|-f\s+(\S+makefile)\|i; } __DATA__ make -r -f ..\../tools/cell/makefile cell.lib` [download] Depending on how you're testing your regex, your problem could be whether you're escaping the "\" in your string.	[reply] [d/l]
Re: using regular expression to extract subset from a line by perlsen (Chaplain) on Dec 31, 2004 at 04:16 UTC
I think ur requirement is extract upto the makefile if u wish u can modify ur regexp to as `inputs: ******* #$str='make -r -f ..\../tools/cell/makefile cell.lib'; $str='make -r -f ..\../system-build/ali/text/makefile cell.lib'; regexp: ******** $str=~/(.)\s(\.\.\\(.)\/makefile)/si ; print $2; or $str=~/(.)\s(.\/makefile)/si ; print $2; outputs: **************** ..\../tools/cell/makefile ..\../system-build/ali/text/makefile` [download] Regards Senthil Kumar.k	[reply] [d/l]