Don't assume `ps` to be `/bin/ps` (NixOS compatibility)

[bittner]

The implementation of this GNOME shell plugin assumes that the process list binary ps is located at /bin/ps.

const cmdResult = await execCommand(["/bin/ps", "cax"]);

Unfortunately, this is only the case on FHS compliant Linux distributions. Other distros, such as the popular NixOS have the executable somewhere else, e.g.

$ which ps
/run/current-system/sw/bin/ps

Symptoms

On NixOS, the widget displays the error message instead of container details. (Hightlighting added by me.)

Suggested Solution Approaches

One of:

• Simply refer to the executable as ps (if possible, e.g. by spawning a shell)
• Try to resolve the full path (if there is a utility function that searches the PATH environment variable)