I want to make a list of utilities that come in handy in Gentoo (general Linux tools available in all distributions also appreciated).
What tools and commands do you use and consider helpful in administration of a Gentoo server?
I will update the list with command from answers from time to time.
Utility for cleaning distfiles and binary packages.
Usage example: eclean distfiles
Usage example output: Cleans out the files in /usr/portage/distfiles. Pretty handy.
Very useful tool for getting information about a package. Similar to "emerge -s" but much faster and more precise.
Usage example: eix gentoolkit
Usage example output: Show information about package such as: available versions, masked versions, installed versions and description.
Check system for obsolete, redundant, uninstalled entries in package.keywords, package.mask, package.unmask, package.use and package.cflags
Usage example: eix-test-obsolete
Usage example output: Shows non-matching entries, redundant entries, and uninstalled entries.
Another very useful tool for getting information about packages (listing package files, checking which files belong to which package and much more)
Usage example: equery b emerge
Usage example output: Show which packages installed a file called emerge
Utility for extracting information about emerged ebuilds
Usage example: genlop -l --date yesterday
Usage example output: Show a list of packages that have been emerged yesterday
Checks system if it's affected by GLSAs (security issues)
Usage example: glsa-check -l affected
Usage example output: List of GLSA that the system is affected by.
Utility for managing (adding, deleting) runlevel scripts.
Usage example: rc-update add syslog-ng default
Usage example output: Adds syslog-ng to default runlevel.
Scans libraries and binaries for missing shared library dependencies
Usage example: revdep-rebuild
Usage example output: Gather binaries and libraries information, check for dependencies, rebuild packages with missing dependencies