Quick write some notes to a file with cat. Ctrl+C when you have finish.

This is a quick and easy way of encrypting files in a datastream, without ever really creating an output file from gpg. Useful with cron also, when file(s) have to be sent based on a set schedule.

Some malicious program appends a iframe or script tag to you web pages on some server, use this command to clean them in batch.

The sort utility is well used, but sometimes you want a little chaos. This will randomize the lines of a text file.

BTW, on OS X there is no

option! There is also no

These are only in the newer GNU core...

This is also faster than the alternate of:

If the connection works you should see a "hello" on host A. If not: check your cabeling etc :-)

cat -n file : number all line

cat -b file : number only non empty line

see man cat

uuencode the file to appear as an attachment

This just reads in a local file and sends it via email. Works with text or binary. *Requires* local mail server.

This helped me find a botnet that had made into my system. Of course, this is not a foolproof or guarantied way to find all of them or even most of them. But it helped me find it.

Using OpenSSL we can encrypt any input we wish and then use Netcat to create a socket which can be connected to from an externally source (even using a Web Browser)

This will diff your local version of the file with the latest version in svn. I put this in a shell function like so:

middlehost allows ssh access from where you are but not securehost.

Use nice ssh piping to simulate scp through A => B => C

setting up the shell function if left as an exercise for the reader. ;-)

Agent forwarding should avoid password typing.

Uses the data in the /proc system, provided by the acpid, to find out the CPU temperature. Can be run on systems without lm-sensors installed as well.

du only accepts lines ending with a NUL, which can be a pain to create. This solves that issue.

Pipe any output to "grep ." and blank lines will not be printed.

If you want certain files out of a directory hierarchy, this will copy just the listed files, but will create the directory hierarchy in the new location ($DIR/)

Plays the sound of the file, should sound like *some* kind of music, most files sound like static but some are really cool.

variations:

Check out http://bbs.archlinux.org/viewtopic.php?id=70937 for more variations!

semi-dupe--like http://www.commandlinefu.com/commands/view/985/generate-white-noise but with different syntax and program.