To install a package from a package file (a file ending with '.deb'):

To extract all the files from a package file:

To install all packages recursively from a directory:

To remove an installed package (configuration files are not removed):

To purge an installed package (removes everything, including configuration files):

To list partially installed packages:

To list the contents of a package file:

To show information about a package file:

To display details about an installed package:

To list all installed packages:

To list packages matching a regular expression:

To show the status of a package:

To list files installed from a package:

To search for a filename from installed packages using a regular expression:

To search for a particular package using a regular expression based on package names and descriptions (separate arguments can be used to specify multiple search patterns which are and'ed together):

To install packages to fix broken dependencies:

To simulate an "aptitude full-upgrade" (i.e. a full upgrade - to help find packages that are being held back) add "-s":

To download the package .deb:

To download the package source code:

Ubuntu Lucid Lynx 10.04

x11vnc shift key bug

If you are having problems with the shift key when using x11vnc a work around is to use the '-xkb' option until the bug is fixed.

Gnome power manager memory leak

The Gnome power manager (gnome-power-manager) has a memory leak bug that causes it to slowly drain all the memory on your computer (see Launchpad Bug #569273: memory leak in gnome-power-manager for more information, and no Ubuntu has decided not to fix this in Lucid). You can limit the memory leak on desktop systems by opening the power management preferences dialog box (System > Preferences > Power Management) and selecting "Never display an icon" under "Notification Area" on the "General" tab, then click close.

If you need to restart gnome-power-manager you can kill the process by running the following command then opening the "Power Management" dialog again (no need to change any setting, just click on "Close").

For all releases

Restarting X

Ubuntu since Jaunty disables the key combination of CTRL+ALT+BACKSPACE as way to restart X. There are several ways to restore that feature, including modifying /etc/X11/xorg.conf to contain the following:

Alternatively you can use the key combination of 'right-ALT + PRINTSCREEN + k' to restart X.

Compiz

Here is a good article on getting Compiz working under Ubuntu. Note that Ubuntu Hardy includes Compiz, you simply need to enable it and get the Emerald window manager (plus some nice themes).

Monitor Resolution

If you are having problems with the resolution of your monitor under X check out this page for some useful tips. If you need to reconfigure the display you can run displayconfig-gtk, while to change the resolution of your boot screen edit /etc/usplash.conf then run update-initramfs -u. Some other good tips can be found here.

Fonts!

Get the nice aenigma free fonts from here (source).

Some 'fun' fonts are available from here (source).

More font sites:

• dafont.com

To install TTF fonts under Ubuntu:

Managing services

Use 'update-rc.d' to enable/disable a service (see Human-Readable Descriptions of init Scripts for a good list services). For example to disable the service 'servicename' run (you made need to install the sysv-rc-conf package first):

To enable the service 'servicename' run:

Top start or stop a service:

The sysvconfig package contains an ncurses GUI that makes it easy to manage services using the program 'sysvconfig' (you can also use the "Ubuntu BootUp Manager or BUM", installed via the bum package):

The sysvconfig package also contains the 'service' program that can be use to start or stop a service:

Resetting the MySQL root password

This allows you to reset the root password for MySQL.

Adding a PPA repository with a single command

This allows you to add a PPA, just replace PPANAME with the name of the PPA to add (requires the python-software-properties package installed which is only available with 9.10 or later).

Fix for "GPG Error BADSIG"

If you are getting "GPG Error BADSIG" messages when trying to update, such as the following:

Then you need to perform a cleaning of your apt meta data (ref: http://www.virtualbox.org/wiki/Linux_Downloads).

First disable any apt proxies you are using (the following is specific to my setup):

Then clean your apt meta data:

Finally restore any proxy you disabled (once again the following is specific to my setup):