Beefy Boxes and Bandwidth Generously Provided by pair Networks
P is for Practical

Re: output unique lines only

by EdwardG (Vicar)
on Dec 06, 2005 at 16:44 UTC ( #514541=note: print w/replies, xml ) Need Help??

in reply to output unique lines only

Here's one approach -

  • Use STDIN and STDOUT for input and output
  • Use a regex to extract the first 'column'. You could also use split, but since you care only about the first column it may be overkill.
  • Use a hash to gather unique filenames

Put it all together and you will have something like this:

# use strict; # helps prevent silly mistakes use warnings; # helpful when writing code while (<>) { # Reads from STDIN if (/^(\w+)\t/) { # If the line starts with one or more 'word' char +acters followed by a tab... my $filename = $1; # ...assume we've got a filename captured $uniq_fnames{$filename} = 1; # ...and add it to our hash. } } print $_,"\n" for keys %uniq_fnames; # prints to STDOUT, can be piped + to a file

Then you could use this as follows

perl < my_non_unique_list_of_files > my_unique_list_of_fi +les


Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://514541]
and all is quiet...

How do I use this? | Other CB clients
Other Users?
Others chilling in the Monastery: (4)
As of 2018-06-19 05:54 GMT
Find Nodes?
    Voting Booth?
    Should cpanminus be part of the standard Perl release?

    Results (111 votes). Check out past polls.