Simple sh script: rand reorder

Sinope · 09-11-2004, 03:35 PM

I *SHOULD* be able to do this myself, but all the ways I can think of are extremely messy:

I need a shell script (or a C program, or a perl script, or whatever) that will randomly reorder the lines in a file. So simple, but I can't seem to do it in less than 20 or so lines.

i.e.:

cat dictionary.txt | reorder.sh > randomwords.txt

or maybe:

reorder.sh "`cat dictionary.txt`" > randomwords.txt

Where dictionary.txt looks like:

aardvark
aardwolf
...
zz top

Any ideas? Seems like it should already exist, or at least be a simple application of sort, or $RANDOM, or something like that. In the interim, I've been sorting by the fifth character, which is fairly random-looking, but I really need it to be different every time.

Cedrik · 09-11-2004, 04:39 PM

Here is an example in Perl (maybe not the more efficient, though) :

Code:

#!/usr/bin/perl

my $file_orig = shift or die "no input file given";
my $file_new = shift or die "no output file given";

open FILE, $file_orig or die "can't open $file_orig";
my @lines = <FILE>;
close FILE;

my $temp = 0;

open FILE, ">", $file_new or die "can't open $file_new to write in";

while(@lines) {
    $temp = rand($#lines);
    print FILE $lines[$temp];
    splice(@lines, $temp, 1);
}

close FILE;

So you call it as this :

./reorder.pl dictionary.txt randomwords.txt

Sinope · 09-11-2004, 05:24 PM

Thanks a bunch! That looks great, I just don't know enough perl to write something like that myself (read: I know virtually no perl). I made a very slight modification to allow me to use it in pipelines and, more importantly, without reading/writing to disk.

Code:

#!/usr/bin/perl

my @lines = <STDIN>;

my $temp = 0;

while(@lines) {
    $temp = rand($#lines);
    print $lines[$temp];
    splice(@lines, $temp, 1);
}

A call would be:

$ cat dictionary.txt | reorder2.pl > randomwords.txt

Thanks again!