perl

How can I expand variables in text strings?

I have a Perl script where I read in a line from a configuration file that contains a variable name. When I read the line into a variable the variable name that needs to be replaced with the given value is not put in. I am using Config::Tiny to access my configuration file. Example:

configuration file

thing=I want to $this

script

$this = "run";
my $thing = $Config->{thing};
print $thing;

print $thing comes out as I want to $this. I want it to come out as I want to run.

Solution

  • OK, so you're wanting Perl to evaluate your string as opposed to print it.

    This is actually covered in this Perl FAQ: How can I expand variables in text strings?

    In short, you can use the following regular expression:

    $string =~ s/(\$\w+)/$1/eeg;

    BE CAREFUL: Evaluating arbitrary strings from outside of your scripts is a major security risk. A good hacker can exploit this to execute arbitrary code on your server.

    brian's FAQ answer covers some of this.