Bareword found where operator expected at testscript.pl line 12

Your posted script does not have 12 lines. Please post the reduced script and the error messages that it produces instead of making things up.

Also, you have already been told about perlvar and %ENV. Also see Get default login environment.

I have updated the script but other lines are hashed out

Perl tells you line numbers in its error messages. Consider reading these error messages and looking at the lines in your original script that correspond to these line numbers.

As you keep your original script hidden from us, and don't tell us what line numbers Perl tells you for the script you posted, we cannot help you.

The error messages don't match the script you have posted (maybe there's more to the script, and the part that you haven't shown us causes problems?)

Also please read the documentation of system. It doesn't do what you seem think it does.

Also lines like my $bash_profile_run = system(". /home/mrdemo1/pig_profile_tmp); are pointless. The sourcing of the pig_profile_tmp happens only in the subshell that system has spawned for you. And then that subshell exits, and you lose all changes that pig_profile_tmp made to the environment.

Bareword found where operator expected at testscript.pl line 12, near 
+"print " PATH"
  (Might be a runaway multi-line "" string starting on line 7)
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my $bash_profile_run = system(". /home/mrdemo1/pig_profile_tmp);

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Corrected the error but still not getting output

output

/home/mrdemo1/pig.jar
excite.log.bz2         pig_1344241951706.log  pig_1344244494512.log  p
+ig_1344245634547.log  pig.jar             script1-local-results.txt  
+tutorial.jar
excite-small.log       pig_1344243339709.log  pig_1344245480551.log  p
+ig_1344246062938.log  script1-hadoop.pig  script2-hadoop.pig
pig_1344241663743.log  pig_1344243831809.log  pig_1344245595053.log  p
+ig_1344246760544.log  script1-local.pig   script2-local.pig
 PATH IS  and 
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You have been already told to use %ENV to work with these variables. Try something like this:

if (fork == 0) {
 # create a subprocess
 $ENV{myvariablename} = "desired variable value";
 # set the variable
 ...
 exec("/path/to/program","some","program","arguments");
 # run the program
}
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If you need to write shell commands, just run a shell and write your shell commands into it:

open my $shell, "|/bin/sh" || die "$!\n";
print $shell "export var=value\n";
...
print $shell "some complicated shell command # ;(){:|:&};:\n";
print $shell "/run/the/program --with-args\n";
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system <<"END";
export var=value
...
some() {shell commands}
/run/some/program
END
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Aside from the many errors in your script, what you're trying to do won't work. A shell's environment is only passed to its child processes (if exported), not its parent or any siblings. So when you open a subshell with system in line 6 and set some environment variables for that subshell by running a couple of export commands, those variables go away as soon as that subshell closes and the system command returns. They will not be passed to the subshells started by your next two commands.

So you have a few options: only open one subshell, and talk to it with a two-way pipe. That could be done with a module like IPC::Open3, or a few other ways. You could also put your export commands in an file that's automatically sourced by your particular shell, but that would depend on your shell. Another (maybe simplest) option would be to set your environment variables within your Perl script by using the %ENV hash, so they can be inherited by any subshells. No need to try to export them in a dot-profile:

print 'Before setting: ', `echo \$MYVAR`;
$ENV{MYVAR} = 'Howdy all!';
print 'After setting: ', `echo \$MYVAR`;
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my $pig_file = system("ls /home/mrdemo1/pig.jar");
my $bash_profile_run = system(". /home/mrdemo1/pig_profile_tmp);
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nonsense, use something like this instead:

see also opendir, File::basename and readdir