One way:

c:\@Work\Perl\monks>perl -wMstrict -e
"my $data = qq{cfg_a\ncfg_b[2:0]\ncfg_c[4:0]\ncfg_d\n};
 print qq{[[$data]] \n\n};
 ;;
 open my $fh, '<', \$data or die qq{opening string by reference: $!};
 ;;
 my $identifier = qr{ [[:alpha:]] [_[:alpha:]]* }xms;
 my $bracket    = qr{ \[ \d+ : \d+ \] }xms;
 ;;
 while (my $line = <$fh>) {
   my $matched = my ($id, $br) = $line =~ m{
     \A ($identifier) ($bracket?) \Z
     }xmsg;
   die qq{bad line: '$line'} unless $matched;
   printf qq{logic%s%s\n}, map { $_ ? qq{ $_} : '' } $br, $id;
   }
"
[[cfg_a
cfg_b[2:0]
cfg_c[4:0]
cfg_d
]]

logic cfg_a
logic [2:0] cfg_b
logic [4:0] cfg_c
logic cfg_d
[download]

Update: Don't worry about the odd looking

my $data= qq{cfg_a\ncfg_b[2:0]\ncfg_c[4:0]\ncfg_d\n};
...
...
open my $fh, '<', \$data or die qq{opening string by reference: $!};
[download]

#!/usr/bin/perl
use strict;
use warnings;

while (<DATA>)
{
   chomp;
   $_ = "$2 $1" if ( /^(.+)(\[.+)/ ); #swap 2 parts if both exist
   print "logic $_\n";
}   

=Prints
logic cfg_a
logic [2:0] cfg_b
logic [4:0] cfg_c
logic cfg_d 

=cut

__DATA__
cfg_a
cfg_b[2:0]
cfg_c[4:0]
cfg_d
[download]

How to do them ? Please give me a hint

Do you want a hint with the algorithm or do you want a hint with the code? What have you already tried?

Generic Hint: Start with a smaller problem and work up. eg. suppose instead of changing the order of the contents you just wanted to do the prepending with "logic " - do that first as it should be pretty easy given the resources of perlintro, perlrun and print. Can you construct an algorithm to do this? Can you convert the algorithm into code?

We cannot help you if we don't know what's holding you back.

There is nothing wrong with cross-posting questions, but it is considered polite to inform the reader (and provide the link) to prevent duplication of work in various location of the Internet.

For reference, here's the one-liner solution I had posted on that other site before seeing this post here:

$ echo 'cfg_a 
cfg_b[2:0] 
cfg_c[4:0] 
cfg_d '   |  perl -ne '($cf, $num) = ($1, $2) if /(cfg_\w+)(\[\d:\d\])
+*/; print "logic $num $cf\n"; 
' 
logic  cfg_a 
logic [2:0] cfg_b 
logic [4:0] cfg_c 
logic  cfg_d
[download]

Hi

I have two hints

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Use Path::Tiny for convenience , perlintro for basic substitution

Advocacy is one thing, but you've got an issue in your response me thinks...

Advocacy is one thing, but you've got an issue in your response me thinks...

Hi,

What do you mean stevieb?

OP Asked for hints I gave exactly such

When I hit reply there were no code tags used, OP appears to have figured that on his own real quick