Thanks a lot for your explanation. For adding support of CGI, SSL and MySQL
in perl, what modules do i need to install. Please write down the commands
for installing and uninstalling and also for checking that what modules are
installed by default in perl as i have read the apache doccumentation where
it is not mentioned clearly.
Kindest Regards,
Raheel.
On Thu, Apr 16, 2009 at 6:17 PM, Chas. Owens <chas.ow...@gmail.com> wrote:
> On Thu, Apr 16, 2009 at 11:14, Raheel Hassan <raheel.has...@gmail.com>
> wrote:
> > Hello,
> >
> > I have seen some Perl scripts where some times these lines are mentioned
> in
> > the begining of the script can any body explain these lines.
> >
> > *Script-1*
> > use DBI; # What is been called here.
> snip
>
> The use statement[1] loads a Perl module. In this case you are loading the
> DBI
> module. The DBI module gives you the ability to connect to Relational
> Databases.
>
> snip
> > BEGIN #What operation is been
> > performed by Begin
> > {
> > unshift @INC, "/home/LIBS"; #What is the role of unshift and
> @INC
> > unshift @INC, "libdata/perl5/site_perl";
> > }
> snip
>
> Execution of Perl programs happens in a set of phases[2]: BEGIN, UNITCHECK,
> CHECK, INIT, normal code, and END. When you write normal code it executes
> in
> the fifth phase, but you can mark code as belonging to a given phase by
> using a named block like BEGIN {} or END {}. In this case the programmer
> wants this code to run during the BEGIN phase.
>
> The @INC array[3] holds a list of paths to look in for modules. In this
> case the programmer has installed some modules in /home/LIBS and
> libdata/perl5/site_perl and wants Perl to be able to find them, so he/she
> is using unshift[4] to put them at the start of the array.
>
> The code is in a BEGIN block because use statements are also sneaky BEGIN
> blocks (that is they execute in the BEGIN phase), so if the this code were
> not in a BEGIN block Perl would throw an error saying that it couldn't
> find the modules before his/her code could add the paths to @INC.
>
> 1. http://perldoc.perl.org/functions/use.html
> 2.
> http://perldoc.perl.org/perlmod.html#BEGIN%2c-UNITCHECK%2c-CHECK%2c-INIT-and-END
> 3. http://perldoc.perl.org/perlvar.ht...@inc
> 4. http://perldoc.perl.org/functions/unshift.html
>
> --
> Chas. Owens
> wonkden.net
> The most important skill a programmer can have is the ability to read.
>
