This article is from the Frequently Asked Questions for Linux, the Free/Open Source UNIX-like operating system kernel that runs on many modern computer systems. Maintained by David C. Merrill with numerous contributions by others. (v1.0).
A: For distributions that use RPM format packages, use the command:
$ rpm -qa
You need to be logged in as root. You can save the output to a text file for future reference, a command like:
$ rpm -qa >installed-packages
A: For Debian systems, the equivalent command is:
$ dpkg -l
A: For Slackware and Slackware based distributions, look in the directory / var/log/packages.
[Steven J. Hathaway]
There is one file that describes the contents of each *.tgz package installed on your system.