ekeyword — keywording
The ekeyword tool should be used to manipulate
the KEYWORDS variable. Using this tool will guarantee that you
get the correct keyword ordering — manual editing may screw this
up. The usage is ekeyword changes ebuilds. Valid changes are in
the form sparc (to mark stable), ~sparc (to mark
unstable), -sparc (to mark unavailable) and ^sparc (to
remove the sparc keyword). The special all keyword is useful
when doing version bumps — ekeyword ~all foo-1.23.ebuild
will drop all currently present keywords to unstable. See ekeyword(1)
for details.