working with files

texuser74 has asked for the wisdom of the Perl Monks concerning the following question:

I want to extract only those lines that start with "@" character from a input text file.

when i tried the following code, only 1 line is getting extrated(first instance). But there are more than 1 line in input text file that starts with "@".

open(IN, "<input.txt");
while(<IN>)
{
        s#\@(.*?)\n##;my $temp=$1;
        print "output: $temp\n";
}
close(IN);
[download]

Please advise.

20040907 Edit by ysth: code in code tags

Comment on working with files Download Code

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Re: working with files by davorg (Chancellor) on Sep 03, 2004 at 10:46 UTC
`open(IN, 'input.txt') or die $!; print map { "output: $_" } grep { /^@/ } <IN>;` [download] -- <http://www.dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply] [d/l]
Re: working with files by Arunbear (Prior) on Sep 03, 2004 at 10:45 UTC
`open(IN, "<input.txt") or die $!; while(<IN>) { chomp; next unless /^@(+.)/; print "output: $1\n"; } close(IN);` [download]	[reply] [d/l]
Re: working with files by bronto (Priest) on Sep 03, 2004 at 10:54 UTC
`perl -ne 'print "output: $_" if /^\@/' filename` Ciao! `--bronto` The very nature of Perl to be like natural language--inconsistant and full of dwim and special cases--makes it impossible to know it all without simply memorizing the documentation (which is not complete or totally correct anyway). --John M. Dlugosz	[reply] [d/l]
Re: working with files by tachyon (Chancellor) on Sep 03, 2004 at 10:57 UTC
`perl -ne '/^@/ && print' infile > outfile` [download] Use " insead of ' on Win32 cheers tachyon	[reply] [d/l]
Re: working with files by THuG (Beadle) on Sep 03, 2004 at 12:52 UTC
There are lots of good solutions here, but no answers as to why your code isn't working. I suspect it is because of the minimal approach (dot star question) instead of the maximal (dot star) and the attempt to include the newline. I think the answer that includes chomp and the match-at-beginning-of-string caret should work with littlest change to your code, so you can check out the differences. There are slimmer solutions, though.	[reply]
Re^2: working with files by texuser74 (Monk) on Sep 03, 2004 at 13:22 UTC
Thanks for all your help.	[reply]
Re: working with files by rupesh (Hermit) on Sep 03, 2004 at 10:43 UTC
Untested... `use strict; open FH, '<', 'filename'; foreach (<FH>) { print $_ if /^\@/; } close FH;` [download]	[reply] [d/l]
Re: working with files by Anonymous Monk on Sep 03, 2004 at 11:46 UTC
`sed -n /^@/s///p input.txt grep ^@ input.txt \| cut -c 2- awk '/^@/{sub ("@",""); print}' input.txt perl -ane 'length shift' -e@F -F@ -e' or print @F' input.txt` [download]	[reply] [d/l]