Check out the usage of 'trap', you may not have seen this one much. This command provides a way to schedule commands at certain times by running them after sleep finishes sleeping. In the example 'sleep 2h' sleeps for 2 hours. What is cool about this command is that it uses the 'trap' builtin bash command to remove the SIGHUP trap that normally exits all processes started by the shell upon logout. The 'trap 1' command then restores the normal SIGHUP behaviour.

It also uses the 'nice -n 19' command which causes the sleep process to be run with minimal CPU.

Further, it runs all the commands within the 2nd parentheses in the background. This is sweet cuz you can fire off as many of these as you want. Very helpful for shell scripts.

Remove your BASH history and then link it to /dev/null

Best way I know to get rid of .bash_history and don't allow bash to save the current one on exit

Edit: added ~/ before .bash_history, just in case... ;)

this string of commands will release your dhcp address, change your mac address, generate a new random hostname and then get a new dhcp lease.

USAGE: gate listening_port host port

Creates listening socket and connects to remote device at host:port. It uses pipes for connection between two sockets. Traffic which goes through pipes is wrote to stdout. I use it for debug network scripts.

Remove everything in current directory except files starting with "ca".

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.

This command uses the recursive glob and glob qualifiers from zsh. This will remove all the empty directories from the current directory down.

The **/* recurses down through all the files and directories

The glob qualifiers are added into the parenthesis. The / means only directories. The F means 'full' directories, and the ^ reverses that to mean non-full directories. For more info on these qualifiers see the zsh docs: http://zsh.dotsrc.org/Doc/Release/Expansion.html#SEC87

A common mistake in Bash is to write command-line where there's command a reading a file and whose result is redirected to that file.

It can be easily avoided because of :

1) warnings "-bash: file.txt: cannot overwrite existing file"

2) options (often "-i") that let the command directly modify the file

but I like to have that small function that does the trick by waiting for the first command to end before trying to write into the file.

Lots of things could probably done in a better way, if you know one...

Inspired by http://www.commandlinefu.com/commands/view/2573/remove-all-files-previously-extracted-from-a-tar.gz-file. .... yet for zip files

Remove annoying improperly packaged files that untar into the incorrect directory.

Example, When you untar and it extracts hundreds of files into the current directory.... bleh.

avoid rm to be recursive until you complete the command: put the -rf at the end!

It's also possible to delay the extraction (echo "unrar e ... fi" |at now+20 minutes) wich is really convenient!

Pipe whatever you want to this function, it will, if everything goes well, be redirected to a channel or a user on an IRC server.

Please note that :

- I am not responsible of flood excesses you might provoke.

- that function does not reply to PINGs from the server. That's the reason why I first write in a temporary file. Indeed, I don't want to wait for inputs while being connected to the server. However, according to the configuration of the server and the length of your file, you may timeout before finishing.

- Concerning the server, the variable content must be on the form "irc.server.org 6667" (or any other port). If you want to make some tests, you can also create a fake IRC server on "localhost 55555" by using

- Concerning the target, you can choose a channel (beginning with a '#' like "#chan") or a user (like "user")

- The other variables have obvious names.

This one-liner will the *delete* without any further confirmation all 100% duplicates but one based on their md5 hash in the current directory tree (i.e including files in its subdirectories).

Good for cleaning up collections of mp3 files or pictures of your dog|cat|kids|wife being present in gazillion incarnations on hd.

md5sum can be substituted with sha1sum without problems.

The actual filename is not taken into account-just the hash is used.

Whatever sort thinks is the first filename is kept.

It is assumed that the filename does not contain 0x00.

As per the good suggestion in the first comment, this one does a hard link instead:

create an archive of files with access time older than 5 days, and remove original files.

This is useful for command line 'recycle bins' and such like