Ubuntu Linux: Uninstall / Remove Any Installed Software

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Q. I’d like to save some disk space so I’d like to remove unwanted software from my HP laptop. How do I uninstall software under Ubuntu / Debian Linux?

A. Both Ubuntu and Debian Linux provide command line as well as GUI tools to delete / remove binary packages.

GUI Package Management Tool

synaptic is graphical management tool of software packages. It allows you to perform all actions of the command line tool apt-get in a graphical environment. This includes installing, upgrading, downgrading and removing of single packages or even upgrading your whole system.

Just click on System > Administration > Synaptic Package Manager

Now you can select any package and click on Mark for Removal popup meni. You can also start GUI tool from command line, enter:
$ synaptic &

Command Line Package Management Tool

apt-get is the command-line tool for handling packages. It is used for adding / removing / updating packages.

Uninstall / Delete / Remove Package

Just use the following syntax:
sudo apt-get remove {package-name}

For example remove package called mplayer, enter:
$ sudo apt-get remove mplayer

Remove package called lighttpd along with all configuration files, enter:
$ sudo apt-get --purge remove lighttpd

To list all installed package, enter:\
dpkg --list
dpkg --list | less
dpkg --list | grep -i 'http'

Ubuntu Linux stop / disable GNOME GUI ~ X.org

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Q. I don’t need GUI as I’m developing CLI based applications. By default Ubuntu Loads Gnome GUI. How do I disable X.org / Gnome under Linux so that I get text only login?

A. You can use GUI tools or command line tools to disable GDM (Gnome Display Manager) service (/etc/init.d/gdm).

Disable GDM using GUI tools

The Services Administration Tool allows you to specify which services will be started during the system boot process. You can type the command:
services-admin &

Or just click on System > Administration > Services

Now you will be prompted for the administrator password, this is necessary because the changes done with this tool will affect the whole system. After entering the administrator password, the following window is displayed:

Ubuntu Linux stop / disable GNOME GUI (X.org)

Make sure you remove GDM (Gnome login manager) by disabling the the checkbox and close the window.

Enable GDM using Command Line (CLI) tools

Ubuntu comes with rcconf and update-rc.d command. rcconf allows you to control which services are started when the system boots up or reboots. It displays a menu of all the services which could be started at boot. The ones that are configured to do so are marked and you can toggle individual services on and off.

Install rcconf

Use apt-get command:
sudo apt-get install rcconf
Now start rcconf:
sudo rcconf
Again you will be prompted for the administrator password, this is necessary because the changes done with this tool will affect the whole system. After entering the administrator password, the following text based window is displayed on screen:
Ubuntu / Debian Runlevel configuration tool

Next enable GDM service by pressing space bar (check the checkbox) > Click OK to save the changes.

update-rc.d command

This is 3rd and old method. You can enable or disable any service using update-rc.d command.

Task: Disable X.org GUI

Just enter command:
sudo update-rc.d -f gdm remove

Task: Enable X.org GUI

Just enter command:
sudo update-rc.d -f gdm defaults

You can always start GUI from a shell prompt by typing startx command:
startx &

Please note that you can use above tools to enable or disable any services under Debian / Ubuntu Linux.

See also:

View log files in Ubuntu Linux

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Q. Can you explain me log files in Ubuntu Linux and how do I view logs?

A. All logs are stored in /var/log directory under Ubuntu (and other Linux distro).

Linux Log files and usage

=> /var/log/messages : General log messages

=> /var/log/boot : System boot log

=> /var/log/debug : Debugging log messages

=> /var/log/auth.log : User login and authentication logs

=> /var/log/daemon.log : Running services such as squid, ntpd and others log message to this file

=> /var/log/dmesg : Linux kernel ring buffer log

=> /var/log/dpkg.log : All binary package log includes package installation and other information

=> /var/log/faillog : User failed login log file

=> /var/log/kern.log : Kernel log file

=> /var/log/lpr.log : Printer log file

=> /var/log/mail.* : All mail server message log files

=> /var/log/mysql.* : MySQL server log file

=> /var/log/user.log : All userlevel logs

=> /var/log/xorg.0.log : X.org log file

=> /var/log/apache2/* : Apache web server log files directory

=> /var/log/lighttpd/* : Lighttpd web server log files directory

=> /var/log/fsck/* : fsck command log

=> /var/log/apport.log : Application crash report / log file

To view log files at shell prompt

Use tail, more, less and grep command.
tail -f /var/log/apport.log
more /var/log/xorg.0.log
cat /var/log/mysql.err
less /var/log/messages
grep -i fail /var/log/boot

View log files using GUI tools using the GNOME System Log Viewer

System Log Viewer is a graphical, menu-driven viewer that you can use to view and monitor your system logs. System Log Viewer comes with a few functions that can help you manage your logs, including a calendar, log monitor and log statistics display. System Log Viewer is useful if you are new to system administration because it provides an easier, more user-friendly display of your logs than a text display of the log file. It is also useful for more experienced administrators, as it contains a calendar to help you locate trends and track problems, as well as a monitor to enable you to continuously monitor crucial logs.

You can start System Log Viewer in the following ways:

Click on System menu > Choose Administration > System Log:
View log files in Ubuntu Linux
(The GNOME System Log Viewer)

Note you can start the GNOME System Log Viewer from a shell prompt, by entering the following command:
$ gnome-system-log &

Buffer I/O error on device fd0, logical block 0 error and simply soultion

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I have a CentOS 5 server running on Dell server hardware. I am getting the following error message in my /var/log/messages file (some time message is also display on the console):

Jul 05 12:04:05 dell01 kernel: end_request: I/O error, dev fd0, sector 0
Jul 05 12:04:05 dell01 kernel: Buffer I/O error on device fd0, logical block 0
Jul 05 12:04:18 dell01 kernel: end_request: I/O error, dev fd0, sector 0
Jul 05 12:04:18 dell01 kernel: Buffer I/O error on device fd0, logical block 0
Jul 05 12:04:30 dell01 kernel: end_request: I/O error, dev fd0, sector 0
Jul 05 12:04:42 dell01 kernel: end_request: I/O error, dev fd0, sector 0

What do they mean? How do I fix this problem on Linux based system?

FTP site at osuosl to download Linux ISO / Software

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Q. Can you give me FTP site address at osuosl, so that I can download Linux ISO and other software?

A. The Open Source Lab (osuosl) facilitates open source communities and the development and distribution of Open Source Software (OSS). They provide hosting projects and developing software via their web site. The Open Source Lab is a group at Oregon State University dedicated to supporting and developing Open Source software. A wide range of projects are hosted at the lab including Gentoo, Mozilla, Debian, Freenode etc.

osuosl FTP site

Visit ftp site to download Ubuntu, Apache, Slackware, Gentoo, and other OSS software.