Matthew Lenz

I was recently looking for a good way to check a specific url for response codes using curl. I came across the following blog post. Kudos to the author for posting the solution.

If you are sure you have mod_perl running and are using cache_debug to diagnose issues with repeated cache LOAD and cache MISS with HTML::Template then the following information might be useful.

Digging through the HTML::Template source I discovered the following:

my @key = ($options->{filepath});
push(@key, @{$options->{path}});
push(@key, $options->{search_path_on_include} || 0);
push(@key, $options->{loop_context_vars} || 0);
push(@key, $options->{global_vars} || 0);

The key under which the cached template is stored is a md5_hex of the previous values passed to the HTML::Template->new() method.  If you are pre-loading your templates in your startup with one set of any of these parameters but are later loading the same template with another set then you will see another CACHE LOAD.

For example if you pre-cache in your startup with:

HTML::Template->new( filename => '/my/path/templates/t.html', cache => 1);

and later in a Registry cgi you create a template object with:

my $tmpl = HTML::Template->new( filename => '/my/path/templates/t.html',  cache => 1, global_vars => 1);

you will see a CACHE LOAD rather than a CACHE HIT when /my/path/templates/t.html is loaded.  The end result is that you maybe loading and caching multiple copies of the same template unnecessarily and wasting memory.

If you are attempting to satisfy dependencies for perl software that was NOT available via your favourite repository (this is sometimes unavoidable in enterprise environments) you should AT LEAST attempt to satisfy those dependencies using said repository. The easiest solution is to install ‘apt-file’ from your repo and for any perl modules you can simply call:

apt-file search "LWP::UserAgent"

This will return the following list on Debian Lenny:

liblwp-useragent-determined-perl: /usr/share/man/man3/LWP::UserAgent::Determined.3pm.gz
libtest-mock-lwp-perl: /usr/share/man/man3/Test::Mock::LWP::UserAgent.3pm.gz
libwww-perl: /usr/share/man/man3/LWP::UserAgent.3pm.gz

Now you know that in order to satisfy a dependency on “LWP::UserAgent” you would need to install the ‘libwww-perl’ module from the repo.

If the module is not available via the repo you should next consider installing the package into a custom perl lib directory specifically for the software (and/or user account) in question. To do this read the documentation for the local::lib module in CPAN.

Ultimately your goal should be to not install non-packaged software to /usr/local and by doing so increase the maintainability of your systems.

I’m not sure this affects the newest version of MIME::Lite; however, if you find that you are having issues with your messages being rejected or marked as spam, due to an internal host being added to the Return-Path, the following fix might work for you.

Rather than using:

my $ml = MIME::Lite-new(
    From => ...
    To => ...
    ...
);

$ml->send();

Use the following:

$ml->send_by_sendmail(SetSender => 1);

The perl module you’ll want to install is called PerlMagick (Image::Magick) and rather than loading the image into memory you can just use the Ping method. The Ping method returns an array with 4 elements of information for each page of a multi-page TIFF/PDF. If we divide the number of elements by 4 we know how many pages there are in the TIFF/PDF.

use Image::Magick;

my $im = Image::Magick->new();

my @ping_info = $im->Ping('fax.tif');

## If we access an @rray in a scalar context we get the element count
my $count = @ping_info / 4;

print $count;

There you have it, good luck.

UPDATE:

The example above may or may not work properly with PDF’s.  Even if it does work it appears that ImageMagick makes an external call to the ghostscript (gs) executable on the system to determine the properties of the pdf.  Here is an example that will work for PDFs:

use PDF::API2;

my $pdf = PDF::API2->open('2.pdf');
print $pdf->pages();

I’m guessing that eventually ImageMagick won’t be “broken” but you can use the above in the meantime.