The '[r]' is to avoid grep from grepping itself. (interchange 'r' by the appropriate letter) Here is an example that I use a lot (as root or halt will not work): while (ps -ef | grep [w]get); do sleep 10; done; sleep 60; halt I add the 'sleep 60' command just in case something went wrong; so that I have time to cancel. Very useful if you are going to bed while downloading something and do not want your computer running all night.

it will remove everything except the file names matching you can use also use wildcards

Just refining last proposal for this check, showing awk power to make more complex math (instead /1024/1024, 2^20). We don't need declare variable before run lsof, because $(command) returns his output. Also, awk can perform filtering by regexp instead to call grep. I changed the 0.0000xxxx messy output, with a more readable form purging all fractional numbers and files less than 1 MB. Show Sample Output

Although Exim will purge frozen (undeliverable) messages over time, the command "exim -Mrm #id#" where #id# is a particular message ID will purge a message immediately. Being lazy, I don't want to type the command for each frozen message, so I wrote the one-liner to do it for me.

Remove everything except that file with shell tricks inside a subshell to avoid changes in the environment. help shopt

_ expands to the last argument of the last command that was executed

combines mkdir and cd added quotes around $_, thanx to flatcap! Show Sample Output

Whenever you compile a new kernel, there are always new modules. The best way to make sure you have the correct modules loaded when you boot is to add all your modules in the modules.autoload file (they will be commented) and uncomment all those modules you need. Also a good way to keep track of the available modules in your system. For other distros you may have to change the name of the file to /etc/modprobe.conf Show Sample Output

Requires the dc3dd package - available at http://dc3dd.sourceforge.net Show Sample Output

Usage: titlescroll "message" <width> Requires command "xtitle" or replace with: echo -ne "\e]0;TEXT_HERE\007"

Written by jmcnamara Taken from http://www.perlmonks.org/?node_id=274896 Show Sample Output

With counter format [001, 002, ..., 999] , nice with pictures or wallpapers collections.

Prints the unique IP Addresses as they arrive from an Apache `access.log` file. The '-W interactive' tells awk to start writing to stdout immediately and not buffer the output. This command builds on the uniq lines without sorting command (http://www.commandlinefu.com/commands/view/4389/remove-duplicate-entries-in-a-file-without-sorting.)

Thanks for the comment oshazard, i wasn't aware of purple-remote existence.

This is a more accurate way to watch the progress of a dd process. The $DDPID=$! is needed so that you don't get the PID of the sleep. The sleep 1 is needed because in my testing at least, if you run kill -USR1 against dd too quickly, it will kill it off instead of display the status. So you need to wait a second, probably so that it can configure itself to trap the USR1 signal. Show Sample Output

The following command will clone usb stick inside /dev/sdc to /dev/sdd Double check you got the correct usb sticks (origional-clone)with fdisk -l.

Allows to add more than one ip address to one network device.

the below command create a alias for share your internet connection with another. ifconfig eth0:1 192.168.0.1/24 Its obviously necessary too activate the iptables post-routing and ip forwarding, as root: modprobe iptable_nat iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE echo 1 > /proc/sys/net/ipv4/ip_forward Be sure that the alias 192.168.0.0/24 is not your active real ip range

Adapted using your usefull comments !