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jrdioko

07-20-2006 12:05 AM

Printing random lines of a file

I've been using the remind program to print reminders for various things, and it's usually pretty straightforward to use, but I've run into something I can't figure out how to do. I'd like to be able to get a reminder that is one randomly picked from a long list, rather that something I've scheduled for that specific day. It looks like remind can call a remote program, so I guess it boils down to needing something that will take a file, pick a given number of random lines from that file, and print them out. Any ideas?

puffinman

07-20-2006 12:36 AM

I happen to have already written just such a program, which I use to pick random words from a dictionary file. It should be self explanatory and I hope it helps!

Code:

#!/usr/bin/perl

use Tie::File;

use Fcntl 'O_RDONLY';



my $dict = shift || '/usr/share/dict/words';

my $times = shift || 1;



if ($times == 1) {



  sysopen(DICTIONARY,$dict,O_RDONLY);

  rand($.) < 1 && ($word = $_) while <DICTIONARY>;

  print $word;



} else {



  tie @f, 'Tie::File', $dict, mode => O_RDONLY

    or die "Couldn't open $dict: $!\n";

  my $size = scalar @f;

  $\ = "\n";



  while ($times--) {

    print $f[rand $size];

  }

}

spooon

07-20-2006 12:42 AM

a related questions is answered in perlfaq5

archtoad6

07-20-2006 09:00 AM

I like the algorithm from the Camel Book.

Any interest in trying to it as a bash script? I think this might work (WARNING -- I have tested the pieces, but not the whole):

Code:

#!/bin/bash



N=1

F="path_to_default_reminder_file"



[ $1 -gt 0 ] && N=$1

[ -f $2 ]    && F=$2



C=`wc -l $F`





for ((I=1; $I<=$N; I++))

do

  L=$((RANDOM%$C))

  sed -n "${L}p" $F

done

Mild apologies for the 1 letter variables, old habit that dies hard. (Yes, reinforced by BASIC, but not learned there.)

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