lib/pvl/service: use full /usr/sbin/service path, since debian does not have sbin on user $PATH
## Run test command on given file, outputting results if it fails.
#
# check $src $cmd $args...
#
function test_cmd {
local src="$1"
local cmd="$2"
if cmd_test "$cmd" -q "${@:3}"; then
log_debug "$src: test: OK"
else
log_error "$src: test: Failed"
cmd_indent " " "$cmd" "${@:3}"
return 1
fi
}