There are a variety of package systems.

Operating systems

package system tool web-based access
Ubuntu [[Advanced Packaging Tool|apt-get]], [[dpkg]] packages.ubuntu.com
Debian [[Advanced Packaging Tool|apt-get]], [[dpkg]] packages.debian.org
Red Hat Enterprise Linux [[Yellowdog Updater, Modified|yum]] rhn.redhat.com
Gentoo [[Portage (software)|portage, emerge]] packages.gentoo.org
more

Programming language, third-party libraries

package system tool web-based access
Perl cpan, cpanm metacpan.org
Python [[Pip (Python)|pip]], easy_install pypi.python.org
Ruby [[RubyGems|gem]] rubygems.org
Node.js [[npm]] search.npmjs.org
more

Programming language, entire interpretter

Python pythonbrew
Perl perlbrew
Ruby rvm
Node.js nvm

equivalent commands

apt-get yum cpan
install a package apt-get install pkg yum install pkg cpan pkg
list packages installed dpkg -l rpm -qa cpan -l
all apt-cache pkgnames yum list gzip -dc ~/.cpan/sources/modules/02packages.details.txt.gz
search available packages apt-cache search keyword yum search keyword cpan <<< d /keyword/
show summary info for package any apt-cache show pkg yum info pkg
installed dpkg -s pkg perldoc module
list files in package installed dpkg -L pkg rpm -ql pkg perl -MExtUtils::Installed -le'$,=$/;print ExtUtils::Installed->files(shift)' module
any apt-file list pkg repoquery -q -l pkg
list packages that own a file all apt-file search filename repoquery -q --file filename
installed dpkg -S filename yum whatprovides filename