When running in a browser

Surely you mean: when running in a web server? There's no browser I am aware of which is able to run perl scripts (i.e. has an embedded perl.)

The system user which runs the web server surely has no access to /root on a well behaved system. /root is an utterly inappropriate place to install modules meant to be used system wide.

Consider installing them in a world readable place. Run perl -V:sitelib to find out where perl expects local modules to be.

G'day natol44,

Whatever Perl you're using for your browser script is not the same as the one you used when installing Digest::MD5::File.

If you run these two, you'll see different @INC lists:

/path/to/browser/perl -V
/path/to/root/perl -V
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You should install Digest::MD5::File using the /path/to/browser/perl environment.

Consider whether you should be modifying the 'root' Perl at all. Doing so is generally a bad idea. I don't know what OS you're using; however, the 'root' Perl is typically part of the OS and often has specific patches such that it works in a way expected by the OS. Adding a new module may seem harmless enough, but it might have dependencies which may be automatically installed, overwriting the version expected by the OS. Take a look at Perlbrew as an alternative way of handling this.

The lib pragma failed due to incorrect usage: it does not take paths to modules as arguments - see the linked doco for details. Using this pragma is just a band-aid solution which I don't recommend: if you go down this path, you'll likely end up with multiple 'use lib ...' statements, in multiple scripts, and a potential maintenance nightmare. Install the module correctly once - do nothing else!

Whatever Perl you're using for your browser script is not the same as the one you used when installing Digest::MD5::File.

Not necessarily, /root/perl5/lib/perl5 makes it look like OP used local::lib under root to install the module. shmem already noted some of the problems with that, although I agree with your advice not to modify the system Perl, at least not with cpan or cpanm - using the system's package manager is usually okay.

If this happens to be a Debian-based system, you could install the module via sudo apt-get install libdigest-md5-file-perl. Using local::lib, as you appear to have done, might be possible too, as long as you install the modules in a location that the webserver can access, i.e. not /root. We'd need to know more about your server set-up to give you better advice though.

If all this gets too complicated, then note that Digest::MD5::File appears to be a convenience wrapper around the core module Digest::MD5, which you could use instead.

BEGIN {
    push @INC, '/root/perl5/lib/perl5';
}

use Digest::MD5::File qw(file_md5_base64 file_md5_hex file_md5 md5 md5
+_hex md5_base64);
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or you can add it to your @INC path:

BEGIN {
    push @INC, '/root/perl5/lib/perl5';
}
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That's nearly exactly what use lib does: See lib. (use lib unshifts, i.e. the extra directory is searched first, not last.)

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

Same thing: Can't locate Digest/MD5/File.pm in @INC (@INC contains: /root/perl5/lib/perl5 /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 .) at test.cgi line 9.

Same thing: Can't locate Digest/MD5/File.pm in @INC (@INC contains: /root/perl5/lib/perl5 ...

I guess you have a Perl version lower than 5.18:

When require encounters an unreadable file, it now dies. It used to ignore the file and continue searching the directories in @INC [perl #113422].

  # Perl 5.10
$ perl -I/root -MTesting
Can't locate Testing.pm in @INC (@INC contains: /root ...

  # Perl 5.24
$ perl -I/root -MTesting
Can't locate Testing.pm:   /root/Testing.pm: Permission denied.
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Digest::MD5 ... does not include the functions I am using. ... If I remove the "::File" line I get this error...

I didn't mean that Digest::MD5 is a drop-in replacement for Digest::MD5::File, sorry for the misunderstanding. You would need to use Digest::MD5 according to its documented API. (Digest::MD5::File appears to monkey-patch its functions into Digest::MD5, which probably just adds to the confusion.) For example, here's how you might replace the module's file_md5_hex function:

use Digest::MD5;
sub file_md5_hex {
    my $filename = shift;
    open my $fh, '<:raw', $filename
        or die "open $filename: $!";
    my $md5 = Digest::MD5->new->addfile($fh);
    close $fh;
    return $md5->hexdigest;
}
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