perl OPEN function and zless

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

Hello,

Is is possible to use the zless utility and Perl's open function to read a gzipped file?

I tried using open and piping to zless but that did not work. Ultimately, I would like to read a gzipped file line by line with a while loop without unzipping it such as:

open(FILE, '<', $filename) #somehow using zless or other?
while <FILE>
{
  ...do action on each line...
}
[download]

Comment on perl OPEN function and zless Download Code

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Re: perl OPEN function and zless by davido (Cardinal) on Jul 14, 2011 at 21:17 UTC
CPAN: Perl's killer app: PerlIO::via::gzip I don't know how robust this is, but it worked on a simple test script I just tried myself. `use strict; use warnings; use autodie; use PerlIO::via::gzip; my $filename = 'example.txt.gz'; open my $fh, "<:via(gzip)", $filename; while ( <$fh> ) { print $. . $_; }` [download] I think that's what you seem to be looking for. You could always just open a pipe from the shell instead though. Dave	[reply] [d/l]
Re^2: perl OPEN function and zless by legendx (Acolyte) on Jul 15, 2011 at 15:15 UTC
Thanks, I will look at that but I have used the pipe function from the shell instead for now	[reply]
Re: perl OPEN function and zless by betterworld (Curate) on Jul 14, 2011 at 21:02 UTC
Why would you want to read from zless? It's a pager, which is designed to scroll through a gzipped file (on a terminal). Better choices are 'gunzip' or 'zcat' (maybe look at the man pages). To use these tools with "open", you need to use "-\|" rather than "<". perldoc -f open will tell you more about it. Searching CPAN for gzip might also help. IO::Uncompress::Gunzip is installed with perl by default.	[reply]
Re^2: perl OPEN function and zless by legendx (Acolyte) on Jul 15, 2011 at 15:16 UTC
Thanks, I used this to get it to work: `open(FILE, '-\|', "gunzip -c $filename"); while (FILE) { ..do action.. }` [download]	[reply] [d/l]


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