#compdef chown chgrp
local suf
if [[ CURRENT -eq 2 || CURRENT -eq 3 && $words[CURRENT-1] = -* ]]; then
if [[ $service = chgrp ]] || compset -P '*[:.]'; then
_groups
else
if [[ $OSTYPE = (solaris*|hpux*) ]]; then
suf=':'
else
suf='.'
fi
compset -S '.*' && unset suf
_users -S "$suf" -q
fi
else
_files
fi