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OS X | UNIX

The Command Line Approach

If you are not comfortable using the Terminal to issue Unix commands, read the Mac OS X Unix Tutorial .

The commands I give here will look something like:

% cd ~

Don't type the '%', just the command that follows it, then hit 'return'. The character after 'cd' in the tilde character.

Fire up the Terminal in Applications/Utilities and put on your Unix hat.

Background Information - Trash Theory

This section gives technical details of how the Mac OS X Trash works. However, it is not necessary to understand such details in order to proceed to the next section - 'Practical Advice - Trash Destruction' - which states the command to actually empty the trash.

Trash is held in a directory called '.Trash' within your home directory. You can view its contents with:

% cd ~
% ls -al .Trash

You should see listed the same items you see when opening the trash icon from the Dock.

Examine the '.Trash' directory itself:

% ls -ald .Trash
drwx------ 3 melkor staff 58 Jun 25 12:08 .Trash

You will see that the permissions for '.Trash' are read and write for yourself (I am user 'melkor'), and no permissions for others. Having write permission on a directory means you can change it - i.e. create and remove files within that directory. The key point here is that having write access to a directory allows one to delete files within that directory no matter what the permissions on that file.

There may be a file owned by 'root', with no permissions for anyone, in your home directory. You can delete it. Yes, you can. You can't view it or change it, but you can delete it. This may seem odd, but the reason is that you are not changing the file itself, only the directory. You are removing the directory entry for that file, and so the file vanishes and the disk space it occupied becomes free. But you are only changing only the directory, not the file.

For example:

No Trash?

If your trash is empty, then you will not have directory '.Trash' in your home directory (OS X 10.1). Trash something using the Finder to create it.

ls -al

Unix command 'ls' lists the contents of the current directory. Option '-a' says to list all files in the directory including the hidden dot files such as '.Trash'

Option '-l' says to display a long listing - list file details such as owners, permissions, and modification date as well as the filename itself.

ls -ald

Unix command 'ls -ald' makes use of option '-d', which says to list the details of a directory instead of the contents.

Immutable Files

The Finder (both OS X and OS 9) shows an immutable file as a locked file. Locking and un-locking are equivalent setting and clearing the Unix immutable flag.

Practical Advice - Trash Destruction

Here are four solutions to the four scenarios listed above.

1 - Nested Directories You Don't Own

One solution is to apply write-permission to all files in the trash. Bit if you do not own some of the files you have to run as root. And if you run as root, you may as well simply delete the lot. So here goes.

% sudo rm -ri ~/.Trash

This will zap all files except those that are immutable or in use.

'sudo' executes the command as root and therefore overrides all permissions
'rm' removes files
'-r' does it recursively - ie to all nested files and directories
'-i' is confirm mode - you will be prompted for each file to delete, and I suggest to use this as a safety precaution. If you have many, many files tedium may set in, so you can replace the '-i' with '-f' (force).

2 - Immutable files

You can check which, if any, files have the immutable flag set by specifying the '-o' option to 'ls'.

ls -alo

drwx------  15 saruman  staff  -       510 Jan  6 23:35 osxfaq

-rw-r--r--   1 saruman  staff  uchg      0 Feb 20 14:04 user-imutable-set

'uchg' indicates that the User Immutable Flag is set. 'schg' indicates that the System Immutable Flag is set (see point 4 below).

Clear the immutable flag of all files, then delete:

% sudo chflags -R nouchg ~/.Trash
% sudo rm -ri ~/.Trash

'chflags' changes a file's flags settings.
'nouchg' clears the user immutable flag ('uchg' would set it)
'-R' does it recursively.

3 - Open Files

You can determine which files in the trash are open, and which application has them open, with the 'fstat' command:

% ls -al ~/.Trash
total 0
drwx------ 5 melkor staff 126 Jun 25 16:43 .
drwxr-xr-x 24 melkor staff 772 Jun 25 16:32 ..
-rw-r--r-- 1 melkor staff 0 Jun 25 16:32 xxx
-rw-r--r-- 1 melkor staff 0 Jun 25 16:43 yyy
-rw-r--r-- 1 melkor staff 0 Jun 25 16:43 zzz

% fstat ~/.Trash/*
USER .CMD PID FD INUM MODE SZ|DV R/W MOUNT NAME
melkor vi 731 3 368860 -rw-r--r-- 0 r / /Users/melkor/.Trash/xxx

...that's the one - 'vi' is editing 'xxx'...

Close the offending files, then attempt to empty the trash again.

If you are unable to close all open files, resort to the method described in the GUI approach.

sudo

sudo (super user do) is a Unix command that allows you to run another command as root. You must enter your admin password (not the root password) when prompted.

A user without administrative privileges cannot use 'sudo'

If you were to accidentally put a space between '.' and 'Trash' :

%rm -rf ~/. Trash

'rm' would apply to both '~/.' (your home directory) and 'Trash' ( a non-existent directory). You would wipe every single file from your home directory. Oops!

That's one reason why I suggest the '-i' option

% rm -ri ~/.Trash

so you get a prompt for each file. Hopefully you will spot your mistake on the first confirmation and avoid loosing anything