Install CPAN modules using cpanm¶

If the new box is going to be used for Perl development, you should install a set of CPAN modules. There are two ways to do this:

​ (a) Install them from the distro repos

​ (b) Build them from source

(a) is faster and more reliable. However, the distro repos don't in- clude a full set of modules. Additionally, repo copies of modules may be outdated.

We may document (a) at a later date. This revision of this document discusses (b).

Advisories:

​ (c) This procedure may take up to an hour or longer ​ (d) Some builds may fail. See below for a work-around.

If a build of a given module fails due to a test failure, one work- around is to disable testing for that module. To do that, replace a command of the form:

  cpanm Foo::Bar

with: cpanm --notest Foo::Bar

If builds fail for other reasons, consult a developer.

To proceed:

  bash -e /root/setupdoc/files/addcpan.sh

Note that:

(a) This must be done as "root" (b) Internet access is required (c) The work-around discussed above may be required

CPAN documentation¶

To see what a given CPAN module does, execute the command "perldoc" followed by a space and the module name. For example:

perldoc Algorithm::FastPermute

CPAN Examples¶

CPAN example: Print a sorted list of all unique permutations of an array. Skip redundant lines.¶

use strict   ;
use Carp     ;
use warnings ;

use Algorithm::FastPermute ('permute');

my @array = qw (dog cat woof meow woof cow milk);
my %list  = ();
permute { $list {"@array\n"} = 1; } @array;
for (sort keys %list) { print; }

CPAN example: Download a file from the Web and store it locally.¶

use strict   ;
use Carp     ;
use warnings ;

use LWP::Simple;

die "Error: Download failed\n"
    unless getstore ("https://google.com/", "/tmp/google.html");
print "File downloaded\n";

CPAN example: Compute and display an MD5 sum. The output is consistent with that produced by "md5sum -b".¶

use strict   ;
use Carp     ;
use warnings ;

use Digest::MD5 qw (md5_hex);

my $data   = "moo\n";
my $md5sum = md5_hex ($data)  ;
print "MD5 sum is: $md5sum\n" ;