storing grep output to variable

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

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Re: storing grep output to variable by blueAdept (Beadle) on Jun 08, 2004 at 16:09 UTC
You're using the shell utility "grep" by virtue of the backtick quoting - not the perl function "grep" which is similar. Here is is a chunk of perl code that will do a case sensisive grep of a file. `open(IN, $ARGV[0]); @foo = grep { m/$ARGV[1]/ } <IN>; print @foo;` [download]	[reply] [d/l]
Re^2: storing grep output to variable by Anonymous Monk on Jun 08, 2004 at 18:01 UTC
Thanks very much everyone! I have gotten the code to work! I went with the following coding: `my @lines = grep /$prop/, <FILE>;` [download] This seems to give the result I was looking for, though it's not exactly identical to any of the great solutions you all gave. Anyway thanks for curing my ignorance of grep - at least partially :)	[reply] [d/l]
Re^3: storing grep output to variable by wolv (Pilgrim) on Jun 09, 2004 at 13:27 UTC
That's the solution I would use myself. I'd just like to make a note that `FILE` type filehandles are global. Instead of globals you should use a lexical filehandle: `open my $file, '<', $filename or die $!`. See `perldoc -f my` and `perldoc perlsub (Private Variables via my())` for an explanation of globals and lexicals.	[reply] [d/l] [select]
Re: storing grep output to variable by pbeckingham (Parson) on Jun 08, 2004 at 15:38 UTC
You are mixing Perl and a utility program in an odd way. Your example looks like it's trying to feed grep a slurp, and you want the file name, not the file contents. Either try: my $output = `/usr/bin/grep "$prop" /path/to/file`; [download] Or try applying a regular expression to the contents of the file using only Perl.	[reply] [d/l]
Re^2: storing grep output to variable by Anonymous Monk on Jun 08, 2004 at 16:02 UTC
I could easily be doing something very odd - I only started learning Perl a few days ago. Is grep not a Perl function? What I am trying to do is to retrieve the line of my file that contains the variable $prop, which is fed in on the command line, and store that entire line in a variable. When I try implementing the code that pelagic sent, I get the entire file output, instead of just the one line I want - odd since the input string is unique.	[reply]
Re^3: storing grep output to variable by pbeckingham (Parson) on Jun 08, 2004 at 19:05 UTC
Yes, grep is a Perl function, but you are doing this: `grep ...` [download] and the backtick operators invoke a shell to run grep, which is also a Unix system utility.	[reply] [d/l]
Re: storing grep output to variable by pelagic (Priest) on Jun 08, 2004 at 15:37 UTC
Your problem are the double-quotes inside the single-quotes. $prop is probably used as searchstring with the $-sign. Update Or are you interested in the matched lines? `my $info = grep "$prop", <FILE>; # or my @lines = grep "$prop", <FILE>;` [download] pelagic	[reply] [d/l]