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symkat
It's missing one of my favorites:

    perl -MData::Dumper\ 999
Quickest way to get the version of a module you're running.
pkrumins
Doesn't work for File::Slurp, which has version 9999.19. :) Otherwise awesome thingy to query module versions.
mike-cardwell
Interesting. I would have done it this way previously:

  perl -MData::Dumper -e 'print $Data::Dumper::VERSION."\n"'
pkrumins
Works for any module:

    $ perl -MLWP::UserAgent\ 999             
    LWP::UserAgent version 999 required--this is only version 5.833.
mike-cardwell 

  mike@server:~$ perl -MLWP::UserAgent -e 'print $LWP::UserAgent::VERSION."\n"'
  5.835
  mike@server:~$
d5ve
Even shorter, as -l appends \n to all prints:

    $ perl -MLWP::UserAgent -le 'print $LWP::UserAgent::VERSION'
pkrumins
Even shorter!

    $ M=LWP::UserAgent && perl -M$M -le "print \$$M::VERSION"
Even even shorter!

    $ M=LWP::UserAgent;perl -M$M -Esay\$$M::VERSION
sliverstorm
This reminds me of that joke in which jokes have been reduced to numbers. It's nearly as obscure, too.
pkrumins
Did Gödel come up with that joke?
jrockway
Well, almost any module:

    $ perl -MFile::Slurp\ 9999
    <hangs forever>
ojosilva
I'm a fan of the "V" module.

   perl -MV=Data::Dumper
"Quicker", if you don't count install time.

   cpanm -n V
stouset
Shit like this is why Perl gets under my skin. The best way to do anything in Perl always seems to be some side effect of a clever hack, instead of actually solving the damn problem expressively.

The equivalent in Ruby?

    gem list $GEMNAME
It's shorter and more clear. Take that, Perl golfers!
brador
Making this for all the different languages would be awesome. I'm thinking PHP, jquery etc. one liners.
wx77
Do any other languages really lend themselves to the one line command tools like perl does?

The only one off the top of my head would be ruby but I don't have that much ruby knowledge to judge.

This kind of thing however is perl's bread and butter.

jbum
Agreed - one reason why I still love Perl so much, despite its obvious warts.
mapgrep
Compared to Ruby, one liners are more efficient in Perl because the normally infuriating cryptic variables and defaults save space. For example in Perl you can run a foreach without naming the current iteration value and it defaults to $_. $_ in turn is the default target for many commands, like print.

So Perl's `print foreach @a` becomes Ruby's `a.each{|a| print a}`. Not so bad but it adds up.

stouset
Ruby:

   print a.join
Perl:

   print foreach @a
Ruby wins!
tikhonj
Here's a page for Haskell: http://www.haskell.org/haskellwiki/Blow_your_mind

It isn't exactly the same--some examples are two or three lines and it's more about coolness than practicality--but it's in a similar spirit, and, more importantly, also interesting.

scrame
The first example:

-- split at whitespace -- "hello world" -> ["hello","world"] words

  unfoldr (\b -> fmap (const . (second $ drop 1) . break (==' ') $ b) . listToMaybe $ b)
 
  takeWhile (not . null) . evalState (repeatM $ modify (drop 1) >> State (break (== ' '))) . (' ' :)
    where repeatM = sequence . repeat
 
  fix (\f l -> if null l then [] else let (s,e) = break (==' ') l in s:f (drop 1 e))
Not really in the same spirit at all.
stouset
That blows my mind, but certainly not in a good way. Ruby:

    $ echo 'hello world' | ruby -e 'p STDIN.read.split'
nemetroid
Be aware that those are four separate examples made to showcase features of the language, the simplest of which being just `words`.

    split.hs:
    main = interact (show . words)

    $ echo hello world | runhaskell split.hs
scrame
OK, thats not really clear from the layout. Your example is clearer, but if you have to put it in a script and pipe stuff to it, its not really a 1-liner.