Re: Update config file parameters

[dbuckhal]

I understand that your config file is probably plain text, but here's an option using Data::Dumper and require.

Start with a configuration format, like a HASH:

perl -MData::Dumper -e '
  $conf = {
    DEVICE => 'eth0',
    ONBOOT => 'yes',
    BOOTPROTO => 'static',
    TYPE   => 'Ethernet',
    IPADDR => '10.9.0.200',
    NETMASK   => '255.255.0.0',
    GATEWAY   => '10.9.1.254',
  };
  open( $fh, ">", "monkConfig.txt" ) or die;
  print $fh Data::Dumper->Dump([$conf],["config"]);
'

Creates a file with this format:

$config = {
            'TYPE' => 'Ethernet',
            'ONBOOT' => 'yes',
            'NETMASK' => 255.255.0.0,
            'GATEWAY' => 10.9.1.254,
            'DEVICE' => 'eth0',
            'IPADDR' => 10.9.0.200,
            'BOOTPROTO' => 'static'
          };

Then use require to access the data:

perl -le 'require "monkConfig.txt";
  print $config->{'TYPE'};
'

__output__
Ethernet

...then redo the Dump to write changes back to file. Yeah, probably a bit more tedious then Tie::File, but imagine the possibilities!

[afoken]

here's an option using Data::Dumper and require

Please DON'T use this "solution"!

This opens a HUGE vulnerability, simply because require $filename;, use $filename;, do $filename;, and eval $filecontent; all treat the configuration file as executable code.

See also Re^2: conf file in Perl syntax, Re^2: Storing state of execution.

Or just imagine someone successfully executing echo 'system "/bin/rm -rf /";' >> monkConfig.txt before root executes perl -le 'require "monkConfig.txt";'.

Also, use and require load each file only once, unless you start messing with %INC.

Alexander

[dbuckhal]

Wow, I did not know require would execute the content of the file.

Very good to know. I am glad you found my post and corrected it.

Thanks!

[afoken]

I did not know require would execute the content of the file.

Think about it: How else could require and use (which is just require wrapped in a BEGIN block, and optionally a call to an import method) load and initialise a perl module? How would module Foo load a module Bar that it depends on, if not by executing use or requrie in Foo when the main program requires or uses Foo?

Alexander