I've got this posted in one of my .bash_profiles for humor whenever I log in.

This will give you the Dell Service tag number associated with your machine. Incredibly useful when you need that number for tech support or downloads.

This command tar?s up a directory and sends the output to gzip, showing a rate of 223MB/s.

This may require you installing the pv command.

For debian based users out there:

Sets the Open Firmware to ask for password when selecting a boot volume other then the hd

I sometimes have large files of MAC addresses stored in a file, some databases need the information stored with the semicolon (makes for easier programming a device) others don't. I have a barcode to text file scanner which usually butchers MAC addresses so this was the fix> I initially did this in awk ;)

awk '{for(i=10;i>=2;i-=2)$0=substr($0,1,i)":"substr($0,i+1);print}' mac_address_list

WARNING! This command may set an invalid permission under your current directory.

This command will set the 0755 permissions to all directories under your current directory. An alternative version of this command is: find ~/.ssh -type d -exec chmod 0700 {} \;

WARNING! This command may set an invalid permission under your current directory.

This command will set the 0644 permissions to all files under your current directory. An alternative version of this command is: find ~/.ssh -type f -exec chmod 0600 {} \;

This command will erase all bytecode versions of Python modules under the current directory.

Requires: imagemagick and graphviz

On Debian systems, displays a graph of package dependencies. Works also with other image formats, like svg :

List the commands you have the right to use with sudo.

Adds a newline to the end of all cpp files in the directory to avoid warnings from gcc compiler.

This comes in handy if you have daemons/programs that have potential issues and stop/disappear, etc., can be run in cron to ensure that a program remains up no matter what. Be advised though, if a program did core out, you'd likely want to know why (gdb) so use with caution on production machines.

Requires: signing-party (on Debian).

Note: you need a working MTA on your machine.

Opens a new shell as root. Useful if you want to run a lot of commands as superuser without needing to sudo each of them.

This command would be useful when it is desirable to list only the directories.

Other options

Hidden directory

Other path

Long format:

This is the solution to the common mistake made by sudo newbies, since

does NOT add to the file as root.

Alternatively,

should be replaced by

And you can add a >/dev/null in the end if you're not interested in the tee stdout :

This is a command you see mentioned alot by Gentoo monkeys.

They say to use it after every update of GCC, any library you might use and glibc.

They argue that compiling and recompiling everything like this will optimize the system alot more because you are recompiling the entire system (gcc, glibc etc) with nativly compiled versions of themselves. Same goes for all libraries etc.

I doubt the difference in working speed is really worth the hours and hours you end up having your computer compile the same stuff again and again though.

On Debian systems, choose which command provides java. Works for all alternatives listed in /etc/alternatives.

First you need to instal aircrack-ng

Use this command if you need to put your wireless card into monitor mode.

interface = wlan0 || wifi0 || ath0 et ceatera...

channel = 6, 11, 10, 9 et ceatera

This is a little bash script that will take all files following the *gz pattern in the directory and apply the tar -zxvf command to them.

Have you ever had to scp a file to your work machine in order to copy its contents to a mail? xclip can help you with that. It copies its stdin to the X11 buffer, so all you have to do is middle-click to paste the content of that looong file :)

This is useful when you want to copy a file and also force a user, a group and a mode for that file.

Note: if you want to move that file instead of copying it, you can use

which will remove the file only if the install command went fine.