dpkg -l


List all installed packages.

EXAMPLES:

dpkg returns a number of installed packages:

$ dpkg -l | wc -l
1209

ask dpkg to return only packages related to php. This will include installed and non-installed packages:

$ dpkg -l *php*

Using dpkg with grep to see only installed packages

dpkg -l | grep php

dpkg -L <package>

dpkg -L will show whether the package is installed. If the package is installed dpkg will show related files and their locations whithin the filesystem.

EXAMPLES:

$ dpkg -L ntpdate
/.
/etc
/etc/network
/etc/network/if-up.d
/etc/network/if-up.d/ntpdate
/etc/logcheck
...

$ dpkg -L php5-json
Package `php5-json' is not installed.

Here are simple steps on how to install custom build or existing Debian kernel within a chroot environment. In this example we do not install a new version of Debian in chroot environment but we use the existing installation. Let's create directory for a chroot environment:

Make directory

# mkdir -p /mnt/chroot

First we need to mount a partition with existing Debian installation. In our case a / partition of existing installation is /dev/hdb1 .

# mount  /dev/hdb1 /mnt/chroot

Install prerequisites

jdownloader is a great tool to download file from share websites like rapidshare.com and many more. Here are simple steps on how to install jdownloader on Ubuntu or Debian Linux distributions:
First install all prerequisites:

apt-get install openjdk-6-jre sun-java6-jre default-jre \
zenity default-jre-headles sun-java6-bin \
openjdk-6-jre-headless

Installing this plugin on any Linux system should be a easy task. First download google-talkplugin_current_i386.deb package. On a Ubuntu system use:

sudo dpkg -i google-talkplugin_current_i386.deb 

on a system where sudo is not present by default first change to root:

su

and then enter:

dpkg - i google-talkplugin_current_i386.deb

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