On my Arch systemd install, the name of the root mount unit is -.mount. (It is not listed in /etc/fstab, rather, it get the details of the root mount for the kernel options specified in the boot manager.)

If I try run any systemctl command on this unit, e.g:

systemctl show -.mount

I get this error:

systemctl: invalid option -- '.'

It is confusing the unit name for a option argument. How do I do this? Is there some why to escape the name so that it is not confused for a option argument?

2 Answers 2


By commonly used rules of specifying command-line parameters, a dash in front of an argument makes it interpreted as a short option.

More precisely, -.mount is interpreted as 6 consecutive options, equivalent to: -. -m -o -u -n -t.

To avoid this, place two dashes (--) in front of an argument:

systemctl show -- -.mount

This will ignore any option parsing in the remainder of the command line.


Mountpoint paths can be used to specify a .mount-type unit in any subcommand of systemctl, so you can do

systemctl show /
  • Beautiful. I did not know of this possibility. However, I'd rephrase a bit (see suggested edit)...
    – intelfx
    Jan 16, 2015 at 12:08

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