Trash Can Utilities

One of the simplest ways to recover "deleted" files is to not delete them at all. This is the idea behind a trash can—a tool or procedure to hold onto files that are to be deleted without actually deleting them. These files can be deleted automatically or manually, depending on the tool or procedure. The most familiar form of trash can utility for most users, and the one from which the name derives, is the trash can icon that exists in many popular GUI environments, including KDE and GNOME. To use a GUI trash can, you drag files you want to delete to its icon. The icon is basically just a pointer to a specific directory that's out of the way or hidden from view, such as -/Desktop/Trash or ~/.gnome-desktop/Trash. When you drag a file to the trash can, you're really just moving it to that directory. If you subsequently decide you want to undelete the file, you can click or double-click the trash can icon to open a file browser on the trash directory. This enables you to drag the files you want to rescue out of the trash directory. Typically, files are only deleted from the trash directory when you say so by right-clicking the trash can icon and selecting an option called Empty Trash or something similar.

When you're working from the command line, the rm command is the usual method of deleting files, as in rm somefile.txt. This command doesn't use anything akin to the trash directory by default, and depending on your distribution and its default settings, rm may not even prompt you to be sure you're deleting the files you want to delete.

You can improve rm's safety considerably by forcing it to confirm each deletion by using the -i option, as in rm -i somefile.txt. In fact, you may want to make this the default by creating an alias in your shell startup scripts, as described in Chapter 4, "Mastering Shells and Shell Scripting." For instance, the following line in -/.bashrcor /etc/profile will set up such an alias for bash:

This configuration can become tedious if you use the -r option to delete an entire directory tree, though, or if you simply want to delete a lot of files by using wildcards. You can override the alias by specifying the complete path to rm (/bin/rm) when you type the command.

Forcing confirmation before deleting files can be a useful preventive measure, but it's not really a way of recovering deleted files. One simple way to allow such recovery is to mimic the GUI environments' trash cans—instead of deleting files with rm, move them to a holding directory with mv. You can then empty the holding directory whenever it's convenient. In fact, if you use both a command shell and a GUI environment that implements a trash can, you can use the same directory for both.

If you or your users are already familiar with rm, you may find it difficult to switch to using mv. It's also easy to forget how many files have been moved into the trash directory, and so disk space may fill up. One solution is to write a simple script that takes the place of rm, but that moves files to the trash directory. This script can simultaneously delete files older than a specified date or delete files if the trash directory contains more than a certain number of files. Alternatively, you could create a cron job to periodically delete files in the trash directory. An example of such a script is saferm, which is available from

http://myocard.com/sites/linker/pages/linux/saferm.html. To use saferm or any similar script, you install it in place of the regular rm command, create an alias to call the script instead of rm, or call it by its true name. For instance, the following alias will work:

alias rm='saferm'

In the case of saferm, the script prompts before deleting files, but you can eliminate the prompt by changing the line that reads read answer to read answer=A and commenting out the immediately preceding echo lines. (Consult Chapter 4 for more information on creating or modifying shell scripts such as saferm.) The script uses a trash directory in the user's home directory, -/.trash. When users need to recover "deleted" files, they can simply move them out of -/.trash. This specific script doesn't attempt to empty the trash bin, so users must do this themselves using the real rm; or you or your users can create cron jobs to do the task.

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