how to display commands while perl script executing

[Sunita....@emc.com]

Hi

I want to print the command during script execution .
Example :


===================
$ls = `ls`;

Print "$ls\n";
==================

In the above script I want to print "ls" command before 'ls' command gets executed . Like "set -x" does in shell scripts .

Could you please help me on this ?

Thanks
Sunita

[CloudWebDNS.com]

Hello,

Try this:

$ perl -le '$c="ls -l";print $c;system $c'
ls -l
total 16
drwxr-xr-x 4 pyh pyh 4096 2012-05-12 17:08 backup
drwxr-xr-x 2 pyh pyh 4096 2012-05-13 08:29 bin
drwxr-xr-x 5 pyh pyh 4096 2012-05-03 11:03 ipdata
drwxr-xr-x 4 pyh pyh 4096 2012-05-14 10:34 tmp

[Sunita....@emc.com]

It is working for one line program . How can we implement in a script ?

-Sunita

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[Shlomi Fish]

Hi Sunita,

On Tue, 15 May 2012 07:40:44 -0400
<Sunita....@emc.com> wrote:

> Hi
>
> I want to print the command during script execution .
> Example :
>
>
> ===================
> $ls = `ls`;
>
> Print "$ls\n";
> ==================
>

I should note that trapping the output of "ls" is pretty silly because there
are built-in routines and CPAN modules for doing that which are more portable
and less error-prone than piping to the shell for input.

You also want "print" in all lower-case instead of "Print" with an uppercase
"P".

> In the above script I want to print "ls" command before 'ls' command gets executed . Like "set -x" does in shell scripts .
>
> Could you please help me on this ?
>

You can do it for each and every Perl statement using
https://metacpan.org/module/Devel::TraceVars or maybe using https://metacpan.org/module/Devel::Trace .
If you want to do it only for shell commands executed using backticks, then you
can search for "qx" in http://perldoc.perl.org/overload.html (and you can also
try setting a shell environment variable to add "-x" to all shell-executed
commands).

Regards,

Shlomi Fish

--
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[Michael Rasmussen]

On Tue, May 15, 2012 at 07:40:44AM -0400, Sunita....@emc.com wrote:
> Hi
>
> I want to print the command during script execution .
> Example :
>
> ===================
> $ls = `ls`;
>
> Print "$ls\n";
> ==================

A straightforward way to do this is to run your script with the perl debugger:

perl -d script_name

When it loads you'll see something like:

michael@bivy:~$ perl -d tpl

Loading DB routines from perl5db.pl version 1.32
Editor support available.

Enter h or `h h' for help, or `man perldebug' for more help.

main::(tpl:5): my %index; #### The first executable line of your script

Then press n on your keyboard to run the next command:

DB<1> n
main::(tpl:6): my @file = <DATA>;

And after that just press <ENTER> to execute each command in turn.

As you might imagine you can do other things with the debugger too.

--
Michael Rasmussen, Portland Oregon
Other Adventures: http://www.jamhome.us/ or http://westy.saunter.us/
Fortune Cookie Fortune du courrier:
Happiness is a path, not a destination.
~ Tay Gillespie by way of Mark Canizaro

[Bob McConnell]

> From: Sunita.Pradhan

Are you looking for a Perl script, or just a shell script? Using Perl for this appears to be like using a baseball bat to swat a fly. But here in a Perl mailing list, you are going to get Perl scripts. If that is not what you are looking for, you need to find a mailing list for your particular shell, which you didn't name.

Bob McConnell

[Torqued]

Regards.../om

On 15-May-2012, at 18:23, Bob McConnell <r...@CBORD.com> wrote:

>> From: Sunita.Pradhan
>>
>> I want to print the command during script execution .
>> Example :
>>
>>
>> ===================
>> $ls = `ls`;
>>
>> Print "$ls\n";
>> ==================
>>
>> In the above script I want to print "ls" command before 'ls' command gets
>> executed . Like "set -x" does in shell scripts .
>>
>> Could you please help me on this ?
>

It looks to me she is simply looking for a debugger, set -x in shell helps in debugging the scripts, for perl the best option would be to use 'perl -d script name' option.

> Are you looking for a Perl script, or just a shell script? Using Perl for this appears to be like using a baseball bat to swat a fly. But here in a Perl mailing list, you are going to get Perl scripts. If that is not what you are looking for, you need to find a mailing list for your particular shell, which you didn't name.
>
> Bob McConnell
>
>