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Full Discussion: Cannot execute Unix command in a simple perl script
Top Forums Shell Programming and Scripting Cannot execute Unix command in a simple perl script Post 302558456 by Corona688 on Friday 23rd of September 2011 03:12:47 PM
Old 09-23-2011
[edit] think we crossposted. I still need the -v one though!

---------- Post updated at 01:12 PM ---------- Previous update was at 01:09 PM ----------

Quote:
I have already tested this with shell script and works fine. but i just want to know why the same unix command gives the same result as executed in a shell script
Because, as already explained, this isn't a shell script, this is shell script inside perl, and things are being substituted inside perl before the shell even gets to it.

You can see the same problem in shell code:

Code:
$ NF=slartibartfast
$ echo '{ $NF }'
{ $NF }
$ echo "'{ $NF }'"
{ slartibartfast }
$

If you wanted the literal string $NF, double quotes won't cut it, even if you single quote things inside double quotes.

I'll work on a solution for you. (still need the -v output)
Last edited by Corona688; 09-23-2011 at 04:17 PM..
 

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LEARN ABOUT DEBIAN

pperl

PPERL(1p)						User Contributed Perl Documentation						 PPERL(1p)

NAME

       PPerl - Make perl scripts persistent in memory

SYNOPSIS

	 $ pperl foo.pl

DESCRIPTION

       This program turns ordinary perl scripts into long running daemons, making subsequent executions extremely fast. It forks several processes
       for each script, allowing many processes to call the script at once.

       It works a lot like SpeedyCGI, but is written a little differently. I didn't use the SpeedyCGI codebase, because I couldn't get it to
       compile, and needed something ASAP.

       The easiest way to use this is to change your shebang line from:

	 #!/usr/bin/perl -w

       To use pperl instead:

	 #!/usr/bin/pperl -w

WARNINGS

       Like other persistent environments, this one has problems with things like BEGIN blocks, global variables, etc. So beware, and try checking
       the mod_perl guide at http://perl.apache.org/guide/ for lots of information that applies to many persistent perl environments.

Parameters
	 $ pperl <perl params> -- <pperl params> scriptname <script params>

       The perl params are sent to the perl binary the first time it is started up.  See perlrun for details.

       The pperl params control how pperl works. Try -h for an overview.

       The script params are passed to the script on every invocation. The script also gets any current environment variables, the current working
       directory, and everything on STDIN.

Killing
       In order to kill a currently running PPerl process, use:

	 pperl -- -k <scriptname>

       You need to make sure the path to the script is the same as when it was invoked.

       Alternatively look for a .pid file for the script in your tmp directory, and kill (with SIGINT) the process with that PID.

ENVIRONMENT

       pperl uses the PPERL_TMP_PATH environment variable to determine the directory where to store the files used for inter-process
       communication.  By default, the subdirectory .pperl of the user's home directory is used.

BUGS

       The process does not reload when the script or modules change.

       $^S is not represented identically with respect to perl, since your script will be run within an eval block

AUTHOR

       Matt Sergeant, matt@sergeant.org. Copyright 2001 MessageLabs Ltd.

SEE ALSO

       perl. perlrun.

perl v5.14.2							    2011-11-15								 PPERL(1p)
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