Perl - Modern Perl

Modern::Perl perl module automatically loads :

use warnings;
use strict;
use 5.010;

These are essential stuff to load and "use Modern::Perl;" (17 characters) loads it all. This saves typing and now, more reason to use "strict", "warnings" with "modern" perl features. :)

Adios !!!



Ref :

• CPAN : http://search.cpan.org/~chromatic/Modern-Perl-1.03/lib/Modern/Perl.pm
• Why : http://www.modernperlbooks.com/mt/2009/01/toward-a-modernperl.html

Perl - Apple finally bump Perl to 5.12.3

$ /usr/bin/perl -v

This is perl 5, version 12, subversion 3 (v5.12.3) built for darwin-thread-multi-2level
(with 2 registered patches, see perl -V for more detail)

Copyright 1987-2010, Larry Wall

Perl may be copied only under the terms of either the Artistic License or the
GNU General Public License, which may be found in the Perl 5 source kit.

Complete documentation for Perl, including FAQ lists, should be found on
this system using "man perl" or "perldoc perl".  If you have access to the
Internet, point your browser at http://www.perl.org/, the Perl Home Page.

Although this is not the latest of greatest but this is definitely better of version 5.10.0 :p

Adios !!!

Perl - How to DOS your processor

Here's a way to maximize the CPU processor,

Perl - How to upgrade perl modules

Now we've know how to deal with Perl modules :

• installing em' (the no-brainer way)
• list em' (even the core ones)
• remove em'

How about upgrading Perl modules?

Perl - How to uninstall / delete Perl module

Installing Perl modules can use the cpanm utility, but how about removing Perl modules? App::pmuninstall module is the answer!

Installation :

$ cpanm App::pmuninstall
--> Working on App::pmuninstall
Fetching http://search.cpan.org/CPAN/authors/id/X/XA/XAICRON/App-
pmuninstall-0.16.tar.gz ... OK
Configuring App-pmuninstall-0.16 ... OK
Building and testing App-pmuninstall-0.16 ... OK
Successfully installed App-pmuninstall-0.16

Usage :

Perl - How to find out what Core Modules installed

Perl comes with a set of core modules. Perl core modules comes with default installation.
E.g. :
- Env
- File::Spec
- File::Basename
- Time::localtime

These are just some of the gems to a system administrator. So, how to find out what core modules are included with your perl installation?




Here's how :

Subversion - How to use svn to manage source files

The "svn" command stands for Subversion. Subversion is commonly use to manage revisions of source files, e.g. configuration files & program source code. Subversion keeps revision what of have been change or committed into the repository. This is good when we accidentally change the source code and needs to roll back to the previous changes. It is also good for managing configuration files (e.g. /etc, /usr/local/etc) on servers as it provides revision control. We can roll back to the last working condition if we screw something up. :p

Here's how to start using svn to manage source files, for the first time :

FreeBSD - A great way to track changes of FreeBSD

Before every FreeBSD port upgrade, checking the /usr/ports/UPDATING is a must. It list out known problems with solutions when upgrading ports. Cutting down less hiccups during upgrade of system. Skimming the changes using bare eyes can be quite tiring some times.

This is another fun way of monitoring the changes is, reading the changes in /usr/ports/UPDATING like a web feed, using RSS. Thanks to Alex of versia.com, he created a RSS feed that keep track changes of /usr/ports/UPDATING and publish it through RSS feeds. This is the post that he talks about it and the RSS feed is over here.

By the way, this RSS feed is created using Perl and hosted on github over here. Perl rocks !!!

Perl - A happy note, on N900

The Nokia N900 runs perl :

~ $ perl -v

This is perl, v5.8.3 built for arm-linux-gnueabi-thread-multi

Copyright 1987-2003, Larry Wall

Perl may be copied only under the terms of either the Artistic License or the
GNU General Public License, which may be found in the Perl 5 source kit.

Complete documentation for Perl, including FAQ lists, should be found on
this system using `man perl' or `perldoc perl'. If you have access to the
Internet, point your browser at http://www.perl.org/, the Perl Home Page.

Cheers !!!

Perl - How to change @INC to include non-standard path

Have been playing around with local::lib and bootstrap a few directories. After switching a few local::lib directories, I tend to forget which cpan module is installed in which local::lib directory and this make perl don't know where to find the cpan module. This is how to set the environment variable @INC so that perl can quickly locate the cpan module.

Perl - How to list installed modules

A note for myself. This is how to list out what perl modules are installed.
Way 1 :

perl -MFile::Find=find -MFile::Spec::Functions -Tlwe 'find { wanted => sub { print canonpath $_ if /\.pm\z/ }, no_chdir => 1 }, @INC'

Way 2 :

perldoc perllocal

*** these are all taken from http://perldoc.perl.org/perlmodlib.html

Das Vidanya !!!

Perl - How to install perl module without root or super user

By default, perl modules installed through cpanX (cpanm, cpanp & cpan) utilities are install into system wide perl directory. Although this will make the module available through out all users on this box, it also means if there's a problem with particular module, it affects all users. Some other problem hit me as well :

Problem 1 - bloated with perl modules :
Some modules installed because it was needed to fulfill some dependencies (not necessary useful though), testing purpose or other reasons. This resulted the system wide perl directory is bloated with modules that aren't used as often as it should & should be removed. Removing modules in perl aren't easy as removing packages through a package manager. Because a typical package manager will check for dependencies to make sure that removing 1 package won't break another package.

Removing perl modules typically means manually remove the .pm files (or directory) in perl system wide directory. And this means there is a risk that removing a module might break some program or modules that depends on it.

Problem 2 - no root privileges :
In a hosting environment, normally one doesn't have root or sudo account, which installing CPAN modules needs it to add or change files in perl system wide directory. How nice if a normal users can have their own perl module directory.

Problem 3 - development environment :
Developers likes to setup individual perl projects to test & work on different environment. Naturally sets of modules that can be install into few different directories to serve as environment, switching between these directories are ideal for this situation. In this case, messing up an environment doesn't means messing up the entire perl modules.

Given the above situation, local::lib fits into the picture by solving the problems. Local::lib creates a directory resides in ~/ and cpan modules are install into here afterwards. Local::lib does that by changing the environment parameters @INC & system's $PATH variable.

The below instruction uses the "bootstrap" method of local::lib installation. This is useful on hosting environment where no access for root or sudo execution to install local::lib perl module.

Perl - How to install CPAN module, the easier way

Following IronMan Challenge posts not only for the sake of seeing What Color of Hair & Shirt ends up with Matt but the posts have been much enlightening. Recently in IronMan Challenge, there's been much talk about one of Miyagawa's project, App::cpanminus. Basically, cpanminus is a tool to install perl module from CPAN, without the verbosity of cpan|cpanplus, which also means, more newbie friendly. :)

The beauty of cpanminus is, it does not ask dozens of question before it installs. Instead, cpanminus will use the most suitable defaults & start downloading dependencies and install it. By default, cpanminus will not tell every action and result on the screen, which "scare" less.

In short, cpanminus improves or makes perfect the experience of installing modules from CPAN. Since the first time trying cpanminus, love it and loving it more seems inescapable :p

*** Some assumptions, perl 5.8 at least exist.

Enough talking, here's how to install cpanminus :

Perl - Connect using SSH with Perl & CPAN module

It has been weeks since the last time blogging about Perl. My day to day job has been tying most of my free time and blah blah blah excuses ... :p

My job deals with FreeBSD server, 90% of my time. Daily routines includes checking server health status. FreeBSD has these periodic scripts that will report server health status to sysadm daily, but the emails are always being "ignore" as the info in it are too vast. So, i decided to cough out a simple Perl script that will use SSH to connect to the servers and pull some health status report. This post will talk about using cpan module's, NET::SSH::Perl, to execute commands then print out the results.

Purpose of this script :

• connect to server using ssh
• authenticate only using public key
• run a command and print out the result

Perl modules used :

1. Perl::Critic = perl's best practice
2. Net::SSH::Perl = the basic of using ssh in perl
3. Net::SSH::Perl::Key::RSA = authenticate using public key
4. Class::ErrorHandler = needed by Net::SSH::Perl::Key::RSA module

To reduce the hiccups, install the modules listed above by using CPAN client.

Here is the script :

vim - Commenting multiple lines, block comment

Perl does not have block comment feature. The Acme::Comment module was the easiest way to make Perl do block commenting, with additional features, it allows customization of open & close punctuation mark.

Until yesterday, my first Perl code got some problem and had to seek help from the IRC channel perl-help @ irc.perl.org (these guys are really helpful, thanks dudes!). Just when they were helping me to solve the problem, Caelum tip me on how to block comment in Perl using vim. I thought it was a good idea as it doesn't need to load additional module to handle the block comment thing, which save some CPU processing.

Here it is :

Perl - How to install Perl module using CPAN shell

One of Perl's strength is it's repository of modules, thousands of modules. No need to re-invent the wheel, just think of what you wanna do and search for it (http://cpan.perl.org).

The CPAN modules are available through the CPAN shell. In this post, we will talk briefly about how to install the CPAN shell and show an example of installing a module.

The Perl Ironman Challenge

Ironman Challenge. An effort to promote Perl within its community.

Accidentally stumble upon the challenge while searching for Perl's mailing lists and blogs.

I have always wanted to pick up a programming language. To buck up my system administration skill by scripting daily routines and system monitoring. And most importantly, write some web application with this much fascinated programming language that is well known for its TMTOWTDI (There's more than one way to do it !!!) flexibility.

This is my first post on the Ironman Challenge.

Why did I pick up the Challenge? A way to force myself to document what i have learn and also reminder myself to practice more. 1 post every week but no more then 10 days in between. I'll have to cough up with something i've learn, and i must learn. :p

At the same time, hopefully someone can spot what i have been missing or did wrong during my learning process. All constructive comments and suggestion is much appreciated.

Currently, i am working on converting the bash scripts i have, to perl. Reason to do so is getting a chance to familiarize myself with perl, with a goal. With this purpose, at least i don't bang around like a headless fly. Also, i think my bash scripts are some fast & dirty approach to accomplish things, which i think "use strict;" & "use warnings;" can fix/correct most of it. After a few days or so meddling around, manage to try out some condition & loop statements, date/time functions, database connections modules & some array operations. Huh, this is one topic for blogging.

At this stage, I am still trying to get around the documentation, perldoc. Most of the time, i'll be browsing "perldoc perltoc" to find out which functions and/or modules i can use. Still trying to figure out how to search for modules or functions.

CPAN. Comprehensive Perl Archive Network. There's definitely something for me to use, so that i don't have to "re-invent" the wheel. This is another nature of me, laziness. Re-using other people's code not only fulfill my laziness, but also make me write shorter code to accomplish my task.

The next post i will be talking about how to install & use modules.

That's all for now...

Adios !!!