* guix/scripts/system.scm (resolve-subcommand): New procedure. (process-command): Handle 'search'. (guix-system): Likewise. (show-help): Augment. * guix/scripts/system/search.scm: New file. * po/guix/POTFILES.in: Add it. * Makefile.am (MODULES): Add it. * guix/ui.scm (%text-width): Export. * doc/guix.texi (Invoking guix system): Document it. (Service Types and Services): Mention 'guix system search'. * tests/guix-system.sh: Test it.