perl script HowTo - Linux / Unix Q & A from nixCraft

HowTo: Reverse a String In Unix / Linux Shell?

in BASH Shell, Perl, UNIX last updated July 6, 2012

How do I reverse lines of a file or files under Linux or Unix like operating systems?

Linux / UNIX: Run Commands When You Log Out

in Linux, UNIX last updated November 23, 2010

I’ve written a Perl script that connects to our central server for me and it allows me feed data so that I make a timesheet later. How do I run my script when I log out from Apple OS X or Linux / UNIX workstation using bash shell?

Howto: Write script in Perl

in Linux, Perl, UNIX last updated July 17, 2007

Q. Iâ€™m new to Linux and Perl. Iâ€™ve printed perl man page but it is bit confusing and omits a lot of simple things or details. Can you tell me how do I write a perl script? How do I open perl editor?

A. Larry Wall began work on Perl in 1987 and it is a dynamic programming language. Traditionally perl programs are written using text editor such as vi or emacs. The overall structure of Perl derives broadly from C.

Also when you start learning a new programming language, always start with Hello world program.

Hello world Perl Program

Let us print Hello world from a shell prompt. Type the following command (excluding $ ):
$ perl -e 'print "Hello, world!\n"';
Output:

Hello, world!

Let us write hello world program using vi text editor:
$ vi hello.pl
Append code as follows:
#!/usr/bin/perl print "Hello, world!\n";

Save and close the file. Now setup a execute permission:
$ chmod +x hello.pl
Finally execute perl program:
$ ./hello.pl

First, I used the vi command to create a file named hello.pl
The first line of the script used to specify that the script is to be executed by perl program (#!/usr/bin/perl) and not by a shell.
Print command prints hello world on screen. Please note that the notation \n which stands for newline i.e. print a newline.

FreeBSD find out RAM size Including Total Amount of Free and Used Memory Size

in FreeBSD, FreeBSD Jails (VPS), Hardware, Perl, UNIX last updated September 21, 2016

How do I find out RAM size or memory size installed in my FreeBSD server? How do I display amount of free and used memory in the system powered by FreeBSD? How do I find out how much RAM is installed on a FreeBSD 10 server?

Perl Display And Pass Command Line Arguments With @argv

in Linux, Perl, UNIX last updated July 29, 2013

How do I read or display command-line arguments with Perl?

Perl sprintf: How Do I Use sprintf In a Perl Script?

in Debian / Ubuntu, FreeBSD, Linux, Perl, RedHat and Friends, Solaris-Unix, Suse, UNIX, Windows last updated June 17, 2011

How do I use sprintf() function in a perl script under Linux or UNIX?

How do I send html email from Perl?

in Apache, Debian / Ubuntu, EMail Servers, Perl, RedHat and Friends, Solaris-Unix, Ubuntu Linux, UNIX, Windows last updated November 29, 2007

Q. How Can I send html email from cgi perl program under UNIX / Linux and Apache web sever?

A. Sending HTML email is an easy task with MIME::Lite CPAN module. It is a low-calorie MIME generator.

It can be use to send html emails, graphics file email attachments as a single-part or multi-part message. Here is simple perl script that sends html email.

Install Perl MIME::Lite

If you do not have MIME::Lite module, install using following command (login as a root user):

# cpan -i MIME::Lite

Perl script code

Script to send html email from perl:

#!/usr/bin/perl -w
use strict;
use MIME::Lite;

# SendTo email id
my $email = 'user@somewhere.com';

# create a new MIME Lite based email
my $msg = MIME::Lite->new
(
Subject => "HTML email test",
From    => 'YOU@somewhere.com',
To      => $email,
Type    => 'text/html',
Data    => '<H1>Hello</H1><br>This is a test email.
Please visit our site <a href="http://cyberciti.biz/">online</a><hr>'
);

$msg->send();

Save the script and execute it. Here is an email (sample) send by above script:

Read man page of MIME::Lite for more information:

perldoc MIME::Lite

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