Maybe the reason you can not see the stuff in "a.pl" is because you may need to use "print "Content-type: text/html\n\n";" before you print.
Example:

#!/usr/local/bin/perl -w
use CGI qw(:standard);
#my $name = undef; # is ok, but you'll get a warning if $name is blank
+.
my $name = param("name") || ''; # better for warn!
print "Content-type: text/html\n\n"; # Setup the header for the browse
+r
print "value = ",$name, "\n";
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Once you Get your code to work. I want you to remember to check the param() inputs before you print them, if its going to be used in a public web page!
As your "a.pl" sits now anyone could inject HTML and Javascript codes. that is a security risk if your going to let people you dont trust use the script.

Here is an Example of how to secure your param():

print "Content-type: text/html\n\n"; # Setup the header for the browse
+r
my $name = param("name") || '';
# Allow only numbers, letters and _
if ($name && $name !~ m/^[0-9A-Za-z_]+$/i) {
print 'Error: Bad input Format';
exit; # Stop script
}
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If the code needs a number and no letters just check for numbers in that param().

Good Luck!