Why does launching an application via gksu not work?

Question

I am attempting to automount my backup drive on Ubuntu studio 16.04.1.

I type gksu gedit /etc/fstab in terminal and enter my password, but I cannot see the editor.

Can anyone please help?

Answer 1

When you run gksu or gksudo and attempt to run a command that doesn't exist, you don't usually see an error message.

If the gksu and gksudo commands are not installed, you do see an error message when you try to run them, but if the program you're trying to run is not installed, you do not always see any error message.

I am able to confirm this by running a command that is not installed (gksu blahblah) on a Lubuntu 16.04 system where I know the gksu is installed and working.

The OP was able to solve the problem by checking if gedit was installed and, upon discovering it was not, installing it.

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Besides running gedit as root with gksu or gksudo, another way to edit a system file with a graphical text editor is to use sudoedit (as waltinator has suggested) but set the VISUAL environment variable to the editor you want to use:

VISUAL=gedit sudoedit /etc/fstab

• Setting EDITOR instead of VISUAL also works, provided that VISUAL is not also set; if VISUAL is set and not blank, its value takes precedence. VISUAL doesn't mean "GUI" here.

The filename your editor shows you for the file you are editing will be something like fstab.XXEZgT6C. This is because sudoedit makes a copy of the file, you edit the copy, and your changes (if any) are written to the file when you close the editor. The filename shown in the editor is the name of the temporary copy.

The editor itself runs as your user, not as root, and has your settings, which can be convenient. However, since the sudoedit command only completes and writes your changes once you have quit the editor (not just when you've quit the file in the editor but the editor is still open), you'll probably want to either

• not have that graphical editor already running when you run it, or
• use a graphical editor that is configured so that a new instance is created every time it is run (rather than a new tab or window in the original instance).

In some editors, you can change this in the settings.

Of course, your editor does still have to be installed for this to work. But (as with the gksu/gksudo way) the editor doesn't have to be Gedit; you can use any editor you like.