Quickly install App::cpanminus

I take for granted that cpan is installed in every *nix system, at least I never found a system when this assumption was false. Until today. It seems that some RedHat based distributions, most notably Oracle’s, do not ship cpan. And the fact is that I don’t use cpan at all, preferring cpanm (i.e., App::cpanminus) since I find it simpler and quicker to adopt. But when App:cpanminus is not installed, I use cpan to install it. Ok, so having that both are missing, how to install stuff from scratch? Today I found out a new way to install cpanm that I was not aware of: https://cpanmin.us is a web site that provides a self-contained Perl script that will install automatically cpanm. Note the smarter name in the URL! How to install cpanm with this script? Here it is:
  • use curl to download the Perl text
  • pipe it to your system-wide perl
  • make Perl aware that the result will be App::cpanminus.
For instance: 

% curl https://cpanmin.us/ | perl - App::cpanminus
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  295k  100  295k    0     0   740k      0 --:--:-- --:--:-- --:--:--  742k
!
! Can't write to /usr/local/share/perl5/5.32 and /usr/local/bin: Installing modules to /home/luca/perl5
! To turn off this warning, you have to do one of the following:
!   - run me as a root or with --sudo option (to install to /usr/local/share/perl5/5.32 and /usr/local/bin)
!   - Configure local::lib in your existing shell to set PERL_MM_OPT etc.
!   - Install local::lib by running the following commands
!
!         cpanm --local-lib=~/perl5 local::lib && eval $(perl -I ~/perl5/lib/perl5/ -Mlocal::lib)
!
--> Working on App::cpanminus
Fetching http://www.cpan.org/authors/id/M/MI/MIYAGAWA/App-cpanminus-1.7047.tar.gz ... OK
Configuring App-cpanminus-1.7047 ... OK
Building and testing App-cpanminus-1.7047 ... OK
Successfully installed App-cpanminus-1.7047 (upgraded from 1.7044)
1 distribution installed


When executing as a non-privileged user, the cpanm executable will be installed into the $HOME folder: 

% file ~/perl5/bin/cpanm
/home/luca/perl5/bin/cpanm: Perl script text executable


% ~/perl5/bin/cpanm --version
cpanm (App::cpanminus) version 1.7047 (/home/luca/perl5/bin/cpanm)
perl version 5.032001 (/usr/bin/perl)
...


This is a quick trick to get cpanm up and running without having to deal with ordinary cpan.

The article Quickly install App::cpanminus has been posted by Luca Ferrari on October 8, 2024

Tags: perl