firefoxscreenshot
When I try to use FF headless to take a screenshot of a website by:
firefox -screenshot google.com
FF refuses to run with the following error message:
*** You are running in headless mode.
Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system.
I am running FF 58.0.2.
How do I fix this?
From http://kb.mozillazine.org/Profile_in_use - Check for:
1) A file called .parentlock
-AND-
2) A symlink called lock
...in ~/.mozilla/firefox/random string of alphanumeric characters.default/
The former is present while Firefox is running to prevent more than one different instance from trying to simultaneously write to the same set of profile files, and if Firefox is not closed cleanly, neither may be removed.
Error message received in this case should be:
From anywhere in the filesystem (or removing this if pwd reports ~/.mozilla/firefox/random string of alphanumeric characters.default), replacing random string of alphanumeric characters with the FF profile folder on your computer, do rm ~/.mozilla/firefox/random string of alphanumeric characters.default/.parentlock ~/.mozilla/firefox/random string of alphanumeric characters.default/lock` (assuming the first sentence pans out) to remove them, if there isn't a Firefox process running.
More less-authoritative information here.
As the longDescription for chrome-gnome-shell says, you'll have to set a specific gnome3 and a specific firefox option. To do so, include the following in /etc/nixos/configuration.nix and rebuild:
nixpkgs.config.firefox.enableGnomeExtensions = true;
services.gnome3.chrome-gnome-shell.enable = true;
(Unfortunately, these options aren't listed on https://nixos.org/nixos/options.html)
You don't have to explicitly list chrome-gnome-shell and gnome3.gnome-shell-extensions as system packages, as they will be pulled in as dependencies. The "GNOME Shell integration" Firefox extension will still have to be installed by the user through Firefox, though, as you did.
Best Answer
As the error message tries to say (I get the more explanatory "A copy of Firefox is already open. Only one copy of Firefox can be open at a time."), you cannot have more than one Firefox running at a time using the same profile. One simple solution would be to create a separate profile for screenshots (run once with
firefox -Pto create such a profile, I named mine "screenshots", for example), and then explicitly use the new profile when attempting to create screenshots:You may additionally need
-no-remote, as reported by Stack of Pancakes in a comment.