Re^3: Reading a .txt file under 2 levels of compression

Well, from my understanding of the docs (of which I quoted parts in my previous post), this ought to extract the inner ZIP file from the outer ZIP file, into a string:

use IO::Uncompress::Unzip qw(unzip $UnzipError);
my $file = '2.zip';
my $inner;
unzip $file, \$inner, Name => '1.zip';
[download]

after which you can continue:

my $txt;
unzip \$inner, \$txt, Name => '1.txt';
[download]

and now the text will be in the string $txt. (Caveat: untested)

Apparently the "Name => $name" part is optional if the ZIP archive contains only one file (what they call a "member file"):

Say you have a zip file, file1.zip, that only contains a single member, you can read it and write the uncompressed data to the file file1.txt like this.
unzip $input => $output
        or die "unzip failed: $UnzipError\n";
[download]
If you have a zip file that contains multiple members and want to read a specific member from the file, say "data1", use the Name option
unzip $input => $output, Name => "data1"
        or die "unzip failed: $UnzipError\n";
[download]

Comment on Re^3: Reading a .txt file under 2 levels of compression Select or Download Code

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Re^4: Reading a .txt file under 2 levels of compression by pmqs (Friar) on Jan 12, 2011 at 13:44 UTC
That code will work fine, but here is a variation that means you don't need to uncompress the complete outer zip into memory before accessing the inner one. `use warnings; use strict; use IO::Uncompress::Unzip qw(:all); my $file1 = "all.zip"; my $file2 = "1.zip"; my $first = new IO::Uncompress::Unzip $file1 or die "Cannot open $file1: $UnzipError\n"; my $output; unzip $first => \$output or die "Cannot open $file2: $UnzipError\n";` [download]	[reply] [d/l]
Re^4: Reading a .txt file under 2 levels of compression by LazyIntern (Initiate) on Jan 13, 2011 at 01:04 UTC
Thanks bart for code. It is working! I do have another question regarding the following script: unzip $file, \$inner, Name => '1.zip'; What does \$inner mean? Unzipping file into a temp location called inner?	[reply]
Re^5: Reading a .txt file under 2 levels of compression by pmqs (Friar) on Jan 13, 2011 at 10:56 UTC
When I wrote unzip I wanted to allow flexibility on where it obtained it's input and where it sent its output. Currently the input and output paramers can be a filename, filehandle or in-memory. So, for example `my $inner; unzip "my.zip" => \$inner; # remove all whitespace $inner =~ s/\s+//g; print $inner;` [download] This will uncompress the contents of the file "my.zip" and write the uncompressed data into the variable $inner. The code then makes use of the uncompressed data in this case to remove all whitespace, then print it.	[reply] [d/l]
Re^5: Reading a .txt file under 2 levels of compression by bart (Canon) on Jan 13, 2011 at 12:17 UTC
`\$inner` is a reference to the scalar `$inner`. It allows programmers to change the content of the variable `$inner` without explicitly mentioning it by name in the source. You can just as well use a different variable and it'll work the same. For example: `$apples = 10; $pears = 6; take_one(\$apples); # take one apple take_one(\$pears); # take one pear print "I've still got $apples apples and $pears pears.\n"; sub take_one { my $ref = shift; # a reference $$ref-- # access the value of the referenced scalar }` [download] This prints: `I've still got 9 apples and 5 pears.` [download] For more info, check out perlreftut and perlref. It's easy for a programmer to detect if a value is a reference: just use ref: it'll return an empty string for a normal string, and "SCALAR" for a reference to a scalar. It's a convention among module authors to use a reference to a scalar if you want to actually use the string value as data, instead of as a file name from which you'll read the contents; for example in the various HTML parsing modules.	[reply] [d/l] [select]
Re^6: Reading a .txt file under 2 levels of compression by LazyIntern (Initiate) on Jan 14, 2011 at 00:45 UTC
I see. Usually for Methods I would simply read what it requires and what outputs it will give. In the case of Zip, I couldnt find any sources that says the code is valid (like unzip $file, \$inner, Name => '1.zip'; , it still looks wrong to me but it works). Thanks once again.	[reply]