Q. How do I list all installed packages on Linux or FreeBSD system?
A. Most Linux distributions are based upon rpm or apt-get / dpkg packaging system.
RedHat, Fedora Core, Suse Linux, Cento os all are RPM based distribution
Use rpm command as follows to list all installed packages
rpm -qa | grep 'package-name'
rpm -qa | grep -i '*httpd*'
Debian or Ubuntu Linux distribution
You can use dpkg command to list all installed packages:
dpkg --list | grep 'package-name'
dpkg --list | grep -i '*php*'
Task: OpenBSD list installed package
Use pkg_info command for displaying information on all installed software packages
$ pkg_info | grep 'package-name'
bash-3.1.10_1 The GNU Project's Bourne Again SHell expat-2.0.0_1 XML 1.0 parser written in C gettext-0.14.5_2 GNU gettext package lftp-3.4.0_3 Shell-like command line ftp client libiconv-1.9.2_2 A character set conversion library libstatgrab-0.12_1 Provides a useful interface to system statistics nmap-4.01 Port scanning utility for large networks pcre-6.6_1 Perl Compatible Regular Expressions library pkgconfig-0.20 A utility to retrieve information about installed libraries vim-lite-6.4.6_1 Vi "workalike", with many additional features (Lite package
Task: FreeBSD list installed package
Use pkg_info command as described above.