Also, if your on Windows like me, I open($file, '<', shift) or die "$!"; and then immediately binmode($file);.

Commands or parameters or filenames added to the command line when calling the script get put into an array called @ARGV and when you call shift it increments $ARGV[0] to $ARGV[1] to $ARGV[2] and so on for each shift used.

So, if you used C:\path\to\script\perl my_script.pl file_1.txt outfile.txt then you could use shift again to open() (use three arg open) and instead of printing it to the console window, you can write the output to $outFile.

use strict;
use warnings;

my %hash;

open (my $inFile,  '<', shift) or die "$!";
open (my $outFile, '>', shift) or die "$!";

binmode($inFile);
binmode($outFile);

while (<$inFile> =~ /(\d)\s+(\d)\s+(\d)\s+(\w+)/){
push @{$hash{$4}}, $1, $2, $3;
}

print $outFile "@{$hash{$_}}[0..2] $_\n" for sort keys %hash;
[download]

Usage: C:\path\to\script\perl my_script.pl inFile.txt outFile.txt
[download]

Also, please note this also removes one space from each column per row. As long as that does not corrupt your data set it should be fine. It actually may save you some hard drive space. :)

EDITED: fixed typo in matching patterns, thanks haukex

EDITED: changed and made obvious that the individual needs to make absolutely certain that this does not corrupt anything in their data set.

EDITED: had to add a new paragraph so my second EDIT looked ok.

when you call shift it increments $ARGV[0] to $ARGV[1] to $ARGV[2] and so on for each shift used.

No, shift removes the first element of @ARGV on each call, returning the element it removed.

/(\d)\s*(\d)\s*(\d)\s*(\w*)/

Note that this will also match a line as simple as "123", or really anything that has three consecutive digits, since that's the only thing this regex requires. I would strongly recommend using \s+, \d+, and \w+, and anchoring the regex to the beginning and end of the string with ^ resp. $.

As long as that does not corrupt your data set it should be fine (and i am sure it is fine)

Sorry, but how can you be sure? Some file formats require \t as a column separator.

Update: Expanded the last quote and highlighted the part I was reacting to.

No, shift removes the first element of @ARGV on each call, returning the element it removed.

so shift physically removes the entry in @ARGV? this is interesting and i did not realize that. also thanks for pointing out the problem there, i actually did some reading on matching myself, and was trying some new stuff and forgot to change it back to how it was, so i will go back and change that right now. thanks.

the provided sample data was not '\t'. as far as i can tell it was not tab separated. it was a double space. there is no reason under the sun (that i can think of) to have two white spaces between data, actually spaces between data is kind of flawed in itself really, your better off using a comma or some other separator that is not normally used. anyways, the same regex would match both cases as well. if you want to pick that apart thenyoull have a blast if go further down in the comments below and find the person who matched two words in different columns. that would throw off your data quicker than removing a white space.

EDIT: you also took what i said out of context for the most part, what i said was: As long as that does not corrupt your data set it should be fine (and i am sure it is fine)