Perl Shell Scripts

Ok, but u have to execute the Perl script within the shell dont u?  And is it the case you can do a lot of shell script stuff with PERL i.e i/o file manipulation etc.  So if you wanted to move files fro, Dir Aa to B you would use the appropriate sh commands (Im assuming sh here).  But, if for some reason you wanted to do the same with PERL you would srite the perl script but you would still have to call the script from within sh so effectively you would need to enter the appropriate sh to call the Perl script...

What makes it a shell script is that the interpreter can also be used as a shell.  You don't have to use the scripting language of the shell you are using.  You can use bash as your shell, but use ksh to interpret a script.
For a perl script, perl does not have a shell.  The perl script can be started many ways.  It could be started by cron, by a webserver, another perl script, a shell script, user at a command line, or if you have a graphical interface by clicking an icon configured to run the perl script.

shell scripts are scripts written in the language of a particular shell
perl scripts are scripts written in Perl
Not to confuse things, but there are also these
http://search.cpan.org/~ferreira/Shell-Perl-0.0015/lib/Shell/Perl.pm
http://search.cpan.org/~pardus/Zoidberg-0.96/man1/zoiduser.pod

I like stirring the pot :)

The Perl Shell (psh): It aspires to be your primary login shell.
http://sourceforge.net/projects/psh/
http://www.focusresearch.com/gregor/sw/psh/

Note to self:

Google returns a very different first page of results with "perl shell script" and "perl shell".

Like everything else in the world of software, the confusion comes from the way we use our terminology flexibly, or "loosely" if you like.  There is nothing wrong with this flexibility.  In fact the confusion that ensues, often leads to change.

So, the answer to your question is 'Yes - there is such a thing as a Perl Shell Script'.

There are two possible interpretations of your question:

Firstly, because many people use the term "Shell Script" to describe *any* script that can be executed under *any* shell, then a Perl script *is* a shell script by default.  It's like the phrase 'Shell Script' means a script that is eligible to run under a shell.  This doesn't make the definition correct, and in fact it isn't correct.  The correct definition of a shell script is a script that will run under *this* shell, whatever that shell may be.  If *this* is what you meant by your question, then *any* perl script is an example of a script that runs under a shell.  It doesn't really make a perl script a shell script, but that description will do for most cases.

Secondly, there is also a genuine Perl Shell, called psh.  It's not fantastic, but it's workable, and in that shell, anything you type will be evaulated as a Perl syntaxed command.  You can also group commands into a file (script) and execute that file as a single command, so it is a genuine perl shell, and again any perl script will suffice as an example of a script that will run under psh, although there are a few minor  differences.



Finally, there may be one other piece of information you do not know.  Any script from any shell installed on a server can be made to run under the current shell even if it's different by making a few changes to make that script a unix program.  So, to execute a perl script from under the bourne shell:

1) Add the following line as the FIRST line in your perl script (assuming /usr/bin/perl is the location of perl):

  #!/usr/bin/perl

2) Set the execute bit on the script:

  chmod +x filename.pl

3) Test it:

  ./filename.pl


To avoid any arguments or further debate on the definition of the word 'script' in this context, please consider accepting the following assertions:

1) The word 'script' was coined when there was only one shell, and it refers to a number of commands that can be typed at a prompt being grouped into a file and executed in one go.  Just a simple timesaver.

2) The word shell was coined to describe the program that manages the command line interface, interpreting what you type into system calls.  The word shell is related to the 'layers' of the operating system.  There was a shell *before* bourne shell (/usr/bin/sh) in which you could type system calls, so it is not sufficient to limit the use of the work to the common command interpreters (bash, sh, ksh etc).  The only real requirement is that when the shell is running, you can type commands and they will be processed.  So, what would you call what happens when you type 'perl' at a unix command line (with perl installed! ;) )?

Good definition, well put across I might also add.  However, my interpretation of a Shell script is something which performs the monotonous OS system maintenance tasks.  So in the context of BASH OR SH typing in its native code to PIPE, GREP or whatever combination to produce a script which alleviates the laborious tasks of manually step by step execution.  Then I hear the term 'Shell scripting with Perl' which is where I get confused.  When we use these phrases in the same context does this mean that a perl script is invoked under a specific shell which does specific shell scripting tasks such as user/disk maintenance or any OS specific task etc.  This is where I get confused ya see...  Im quite proficient with Bourne, well used to be, but have had little experience with Perl and absolutely no experience of combining the 2...???