Is there any way to find available CPAN version programmatically? - cpan

Question

I am trying to find CPAN version programmatically, but ends up in failure.
Tried with perl %Config & %ENV, but couldn't find anything there.
my $cpanv = `cpan -v`;
# gives: Loading internal null logger. Install Log::Log4perl for logging messages
My goal is to auto configure cpan programmatically. CPAN config prompt varies by versions.
CPAN asks like[similar]:
1. "Do you want to manually configure?[yes]"
2. "Do you want cpan to configure?[no]"
Any way to find CPAN version or avoiding unattended CPAN configuration?

Answer 1

The cpan command-line program is a wrapper around App::Cpan. As far as I can see, the two files always have the same version number. That means you can do something like this:
use App::Cpan;
my $cpanv = $App::Cpan::VERSION;
Update: There are a few concepts to get straight here.
CPAN.pm is a CPAN exploration module that was added to Perl version 5.004. It includes its own basic shell.
App::Cpan is a wrapper around CPAN.pm which adds an improved command interface. It was added to Perl 5.12.
cpan is a tiny script that uses App::Cpan. It was also added to Perl version 5.12. [Update: that's the current version of cpan - there was also an earlier one that was based on CPAN.pm.]
App::Cpan and cpan share the same version number (currently 1.675). CPAN.pm is older and therefore has a larger version number (currently 2.27).
The version number from App::CPAN is what you get when you run cpan -v - so that's what I've given you in my code.

Answer 2

My goal is to auto configure cpan programmatically.
If you're talking about systems with a known configuration, just create (or modify) ~/.cpan/CPAN/MyConfig.pm. For example, the following is mine:
$CPAN::Config = {
'auto_commit' => q[0],
'build_cache' => q[5],
'build_dir' => q[/home/ikegami/.cpan/build],
'build_requires_install_policy' => q[yes],
'cache_metadata' => q[1],
'check_sigs' => q[0],
'commandnumber_in_prompt' => q[1],
'connect_to_internet_ok' => q[1],
'cpan_home' => q[/home/ikegami/.cpan],
'dontload_hash' => { },
'ftp' => q[/usr/bin/ftp],
'ftp_passive' => q[1],
'ftp_proxy' => q[],
'getcwd' => q[cwd],
'gpg' => q[/usr/bin/gpg],
'gzip' => q[/bin/gzip],
'halt_on_failure' => q[0],
'histfile' => q[],
'http_proxy' => q[],
'inactivity_timeout' => q[0],
'index_expire' => q[1],
'inhibit_startup_message' => q[0],
'keep_source_where' => q[/home/ikegami/.cpan/sources],
'load_module_verbosity' => q[none],
'lynx' => q[],
'make' => q[/usr/bin/make],
'make_arg' => q[],
'make_install_arg' => q[],
'make_install_make_command' => q[/usr/bin/make],
'makepl_arg' => q[],
'mbuild_arg' => q[],
'mbuild_install_arg' => q[],
'mbuild_install_build_command' => q[./Build],
'mbuildpl_arg' => q[],
'ncftpget' => q[/usr/bin/ncftpget],
'no_proxy' => q[],
'pager' => q[less],
'perl5lib_verbosity' => q[none],
'prefer_external_tar' => q[1],
'prefer_installer' => q[MB],
'prerequisites_policy' => q[follow],
'scan_cache' => q[atstart],
'shell' => q[/bin/bash],
'show_upload_date' => q[0],
'tar' => q[/bin/tar],
'tar_verbosity' => q[none],
'term_is_latin' => q[1],
'term_ornaments' => q[1],
'trust_test_report_history' => q[0],
'unzip' => q[/usr/bin/unzip],
'urllist' => [q[http://ftp.osuosl.org/pub/CPAN/], q[http://mirrors.hub.co/CPAN/], q[http://cpan.arcticnetwork.ca/]],
'use_sqlite' => q[0],
'version_timeout' => q[15],
'wget' => q[/usr/bin/wget],
'yaml_load_code' => q[0],
};
1;
__END__
Optionally, you can force the defaults to be used, and modify what needs to be changed. For example,
cpan <<<'o conf init
yes
o conf prerequisites_policy ask
o conf commit
quit
'
o conf init causes the initalization process to be started. yes accepts the defaults. o conf prerequisites_policy ask is an example of changing a default. o conf commit saves the changes.