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This causes cp to detect and omit large blocks of nulls. Sparse files are useful for implying a lot of disk space without actually having to write it all out.
http://en.wikipedia.org/wiki/Sparse_file
You can use it in a pipe too:
$ dd if=/dev/zero bs=1M count=5 |cp --sparse=always /dev/stdin SPARSE_FILE
random(6) - random lines from a file or random numbers
Displays six rows and five columns of random numbers between 0 and 1. If you need only one column, you can dispense with the "for" loop.
This is what I came up to generate XKCD #936 style four-word password.
Since first letter of every word is capitalized it looks a bit more readable to my eyes.
Also strips single quotes.
And yes - regex is a bit of a kludge, but that's the bes i could think of.
This command prints the Date (Not time) from 3 days ago (72 hours ago).
This works on systems without GNU date (MacOSX , Solaris, FreeBSD).
Google just released a new commend line tool offering all sorts of new services from the commend line. One of them is uploading a youtube video but there are plenty more google services to interact with.
Download it here: http://code.google.com/p/googlecl/
Manual: http://code.google.com/p/googlecl/wiki/Manual
Shorter and more straightforward.
Also in perl:
$ perl -e 'print join(":", map { sprintf "%0.2X",rand(256) }(1..6))."\n"'
There's been so many ways submitted to get your external IP address that I decided we all need a command that will just go pick a random one from the list and run it. This gets a list of "Get your external IP" commands from commanlinefu.com and selects a random one to run. It will run the command and print out which command it used.
This is not a serious entry, but it was a learning exercise for me writing it. My personal favourite is "curl icanhazip.com". I really don't think we need any other ways to do this, but if more come you can make use of them with this command ;o).
Here's a more useful command that always gets the top voted "External IP" command, but it's not so much fun:
$ eval $(curl -s http://www.commandlinefu.com/commands/matching/external/ZXh0ZXJuYWw=/sort-by-votes/plaintext|sed -n '/^# Get your external IP address$/{n;p;q}')
A null operation with the name 'comment', allowing comments to be written to HISTFILE. Prepending '#' to a command will *not* write the command to the history file, although it will be available for the current session, thus '#' is not useful for keeping track of comments past the current session.
