Hello,
Eventually, does this program already exist for bash/console ?

Thanks !

if you put the following code in a separate file, call it "doubleFilter.pl" it will filter the file given in
$in to the file in $out. You should set 2 different files. If you want to overwrite the first file comment out the last line (remove the "#"). The new file will be free of direct double lines. (Is that what you wanted?)

#!/usr/bin/perl

$in="/home/me/perl/test.txt";
$out="/home/me/perl/test2.txt";
open(IN,"$in");
open(OUT,"> $out");
while(<IN>){
print OUT if ($_ ne $old);
$old = $_;
}
close(IN);
close(OUT);
#system("mv $out $in");

"man uniq"
Depends if the OP really was only talking of 2 successive identical lines (rather than 3, or 4, or ...)

This remove double lines without sorting:

It exist. Use dos2unix (unix2dos exists also)

Sgrunt!

Wow, it's cool. It exists even an 'unique' function in Linux.

Thank you!!

hmm, after 1600+ posts and now you came to realize that?

well those simple functions, I never find them with apt-cache search.

like unix2dos, unique, ...

its uniq, not unique. doing a listing of :

He ment unique, as "a single one"

'apropos <searchterm>' (aka 'man -k <searchterm>') is a good way to search for useful commands. It will list all man pages related to the term you use.

And don't forget google.

Is there a databank/database for finding useful Bash/sh script?
like for video, mp3, ascii, txt, ... it does exists for visual basic, so why not for linux?