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.

In reply to Re: using regular expression to extract subset from a line by johnnywang
in thread using regular expression to extract subset from a line by ramthen

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