The obstinate trash man

Dec 8, 2013 • alan

This weekend’s pet project was to set up Ubuntu Studio to run on my Macbook Pro.

Ubuntu Studio is a Linux distribution, based on Ubuntu, that comes with lots of audio and video software installed and configured.  I have been wanted to play with Ardour, an open source digital audio workstation, and although it will run on a Mac, it runs much better on Linux.  So I downloaded and burned a copy of the Ubuntu Studio “Live DVD”.  This would allow me to test drive Ubuntu Studio on the Macbook without installing anything on the Macbook’s hard disk.  It worked wonderfully, and so I decided to make a bootable “Live USB” stick as well.  The Live USB stick acts just like the Live DVD, except it also allows you to save files back to the USB stick (obviously, you can’t save files to a read-only DVD).  So I would be able to do my studio work in Linux and save my work when I reboot back into OSX.

I was greeted with a very weird bug in Ubuntu Studio’s desktop system.  Whenever I tried to delete a file, I would get the following error:

Unable to find or create trash directory

What a weird error message!

Ubuntu Studio uses the XFCE desktop environment, which follows the Free Desktop’s “Desktop Trash Can Specification“.  Yes, there are people who write specifications about how trash cans are supposed to work.  There is a utility called “gvfs-trash” that actually handles moving deleted files to the appropriate trash can area.  You can run this command from a shell prompt.

$ gvfs-trash somefile
Error trashing file: Unable to find or create trash directory

There’s that same error message.

I ran the same command with “strace” to figure out what it was doing, and I did a little bit of Googling.  I found this blog post, which told me most of what I needed.

The gvfs-trash system wanted to find a directory called “.Trash-999” in the top level of the filesystem.  It wanted 999 because my user ID number was 999 (run the “id” command to see what your user ID number is).  Inside the /.Trash-999 folder, it also wanted two sub-folders named “files” and “info”.  All three of these needed to have 700 permissions.

Here’s a one-liner that will do it all:

u=$(id -u) ; g=$(id -g) ; sudo mkdir -m700 /.Trash-$u ; sudo chown $u:$g /.Trash-$u ; mkdir -m700 /.Trash-$u/{files,info}

After that, the desktop system could remove files OK, and the gvfs-trash command could as well.

That gvfs-trash command might make a good alias!

alias rm='gvfs-trash'