If you already have some code, show us please. If not, try the following recipe and if that fails, feel free to come back with a code sample that troubles you.

In case your only problem is to remove duplicate URLs, the following recipe might be helpful:

• open file for reading ⁽¹⁾
• read file line by line, while
• extract URL (hint: chomp, split, perlre)
• print ⁽²⁾ line if URL has never been encountered (hint: perlfaq4)
• remember that URL has now been seen (hint: $seen{$url})

^(1,2): Open another file for writing and print to filehandle unless output to STDOUT is sufficient.

Update: Or perform a Super Search with this query for more inspiration...

Update: In response to code presented below:

• Fix1: Change $file_hash{$key} = $value; to $file_hash{$key} //= $value; to save first match only.
• Fix2: Change for my $key (keys %file_hash) to for my $key (sort keys %file_hash) to potentially recover original order of entries.
• Better: Have a look at the original hint again. It allows to process the file without saving the whole contents to memory which is an advantage when processing huge files.
• Extra-Hint: perltidy

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