On 18 Aug 99, at 15:22, Sixto Balicoco wrote:
> I want to have an idea what these are; Common Gateway Interface
> scripting and PERL? - how do they work and why they are essential? ...
> at least in general.
PERL is a programming language, sort of like C or Pascal or BASIC.
Actually, of those it is most like C in style, but most like BASIC in
implementation in that
(a) PERL programs are generally distributed in source (text) form, and
*interpreted* in order to run. This makes them fairly portable -- once an up-
to-date PERL interpreter exists for a machine, most PERL programs will run on
it.
(b) There is some fairly powerful functionality built into the language
itself, especially tools for text editting and pattern-matching. C's
approach is much more minimalist -- if you wanted to do these things in C,
you'd have to either call on an additional library, or code them yourself.
CGI is the "Common Gateway Interface", by which a web browser may request a
web server (program) to invoke other programs on the server (machine) and
(usually) incorporate their output into the page being displayed.
In general, the invoked program may have additional effects (such as when a
page hit-counter updates the number of hits recorded on the server), and
could be written in any language.
But look back to point (a) under PERL, above! A PERL program ("script")
will run on any machine that has a PERL interpreter, and this includes
practically all machines that have web server programs available. So the
developer of a web site that includes code to be invoked via CGI can, by
using PERL, leave themselves a lot of flexibility about which server hosts
the site.
There is no inherent association between PERL and CGI, but it's probably
reasonable to estimate that more than 80% of code invoked via CGI is written
in PERL, and that probably at least 60% of the code that has been written in
PERL has been written for use via CGI.
David G
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