Sunday, February 28, 2010

Debian 10

Perl is available in every *nix systems. It is also available in Windows and MAC computers as well. Perl is a scripting language and manipulates text and binary data. Perl is modular and there are thousands of modules available (E-Mail, XML, HTML, PDF, etc.)
You can do single-line commands through:
perl -e 'single-line command separated with semicolon'

To print Hello World! with Perl:
perl -e 'print "Hello World!\n"; print "How are you today?\n"'

A Perl script should have a shbang reference to the Perl location:

After the shbang reference, you can begin your scripting:
print "Hello World!\n";
print "How are you today?", "\n";

Notice that concatenation is done through the comma ",".

To execute a Perl script, there are two things that can be done. We can use the Perl interpreter:
perl test.pl

Or you can change the execute permission:
chmod u+x perl.pl

Note that the shbang reference is very important for directly executing the file or else the Bash shell would not know that it's a Perl script.

You can pass arguments (parameters) into a Perl script. Arguments are stored in the $ARGV[x] array. The first argument starts with $ARGV[0]:
print "Your first argument is $ARGV[0]"

To pass in arguments:
./test.pl Hello!

Arguments are delimited by spaces. The following example will have Hello in $ARGV[0] and World in $ARGV[1]:
/test.pl Hello World

Perl has the best support for REGEXP. To do a REGEXP match:
if ($ARGV[0] =~ //)
print "$ARGV[0]\n";

You can check for compilation errors through:
perl -c test.pl

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