(Perl) Running the same code for multiple files

Question

As of right now, I have 22 files that and 22 separate, but identical (in task), scripts for each file. Very basically, this is what I have:

file_1.txt, file_2.txt,..., file_22.txt

and for each file, I have a script:

script_1.pl, script_2.pl,..., script_22.pl

that outputs

output_1.txt, output_2.txt,..., output_22.txt

respectively.

What I'm trying to do now is write a script that will run all of the scripts (script_1.pl - script_22.pl) at the same time so I don't have to run all of them separately each time I update my files. The reason why they're all separate is because I don't know how to cycle through file names, and for each file name, assign a new output file. I'm hoping someone could help me with exactly this: a script that will read in all of the files at once, run the script for each file (it's one identical script), and for each file, print out a new output file, as listed above.

Edit: I figured I should include what I have right now. I do have something that works, but it still relies on the fact that I have the 22 separate scripts. What I've been doing is the following:

system("perl script_1.pl");

system("perl script_2.pl");

...

system("perl script_22.pl");

I want to be able to combine everything into one compact script. Any help would be greatly appreciated! Thanks in advance!

If identical scripts why not unify by taking input and output file names as arguements? instead of script_1.pl, it would be ./script.pl file_1.txt output_1.txt — Karthik T
– Karthik T, Commented Jan 8, 2013 at 4:42

Schwern · Accepted Answer · 2013-01-08 04:39:34Z

4

You can get the list of program arguments from @ARGV and then run your code in a for loop.

for my $input_file (@ARGV) {
    my $output_file = $input_file.".out";

    process_file($input_file, $output_file);
}

sub process_file {
    my($input_file, $output_file) = @_;

    ...do whatever you like with the input and output file...
}

Then you can run your program like this:

myprogram file1 file2 file3

And it will read file1, file2 and file3 and produce file1.out file2.out and file3.out.

This is some pretty basic programming and some pretty basic Perl. You should probably back up and read some beginning Perl books. I can recommend Curtis Poe's Beginning Perl which just recently came out.

answered Jan 8, 2013 at 4:39

Schwern

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2 Comments

TLP Over a year ago

It should perhaps be specified that process_file should contain the code for the main script, and not system("script.pl $input $output").

Peter Over a year ago

Thank you! Yeah, I literally just started Perl because of a research project, so I still have a lot of basics that I need to get down. I will definitely check out that book!

jeberle · Accepted Answer · 2013-01-08 04:44:40Z

1

Assuming you have access to Bash:

$ for f in file_*.txt; do script.pl "$f" > "${f/file_/output_}"; done

This will create an output file (output_n.txt) for every input file (file_n.txt). You can drop the double-quotes if you use simple names (no spaces, etc.)

answered Jan 8, 2013 at 4:44

jeberle

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Comments

Karthik T · Accepted Answer · 2013-01-08 04:45:12Z

0

Its been a while since I flexed my perl muscles.. but try this to eliminate your problems.

for(my $index= 1,$index<=22,$index++){
   my $inputfile = "file_$index.txt";
   my $outputfile = "output_$index.txt";

   system("perl OneScriptToRuleThemAll.pl $inputfile $outputfile");
}

Where OneScriptToRuleThemAll.pl is my goofy version of 1 unified script from `script_1.pl .. script_22.pl).

The script would need to be modified to parse @Argv to get the inputfile and outputfile parameters, instead of hardcoding them.

answered Jan 8, 2013 at 4:45

Karthik T

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Comments

mswanberg · Accepted Answer · 2013-01-09 02:14:16Z

0

system "script_$_.pl" for (1..22);

answered Jan 9, 2013 at 2:14

mswanberg

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