Embedded Perl script in Linux shell [duplicate]

Question

Can I invoke Perl script from Unix shell? For example I have bash script in form like:

#!/bin/sh
echo This is bash

i=12
echo $i

perl <<__HERE__
print "This is perl\n";
my \$i = $i;
print ++\$i . "\n";


echo This is bash again
echo $i

Above is just an example.

Is it possible to pass variables from bash to script? Hope I expressed myself correctly and properly. I need to call Perl script which will take values from bash script and use them and then return processed results.

Answer 1

The problem is the dollar signs need escaped. It makes for an ugly, error prone Perl script. Use environmental variables.

#!/bin/bash

export i=12
readarray results < <(perl <<-'__HERE__'
        my $i = $ENV{'i'};
        print "$i\n";
        $i += 1;
        print "$i\n";
        __HERE__
)
for r in "${results[@]}"; do echo $r; done

The quotes around HERE prevents bash from doing variable substitution. The "-" allows the here is document to be indented it tabs.

While this is a nice exercise in the finer points of Bash, why not just code in Perl or Bash alone? Bash does regular expressions, arrays, etc. And Perl can do everything Bash can.