Trasher

Trasher is a small command-line utility that aims to replace rm.

It works by moving items to delete to a trash directory instead of deleting them immediatly. As moving a single item is nearly instant (even when it's a large directory), while deleting items recursively can take quite a long time, Trasher is faster than rm, especially for large directories.

How does it work

When an item is moved to the trash, its name is suffixed by its date of deletion and by an ID which is computed using a double CRC (see technical details).

For instance, when deleting an item named my-files, it will be moved to the trash directory under a name like:

my-files [@ 2020.08.03_11h36m36s.093347700+0200] {IBuc}

This allows you to open the trash directory and see its content without using the Trasher binary. Also, Trasher doesn't use an index file, it only extracts informations from the files present in the trash, so you can move it to another drive without any problem, or even merge two trash directories into a single one!

This renaming also allows to delete multiple items with the same name without any conflict.

You can then then restore items from the trash by specifying their names. If multiple items have the same name, a list of items with the provided name will be displayed along with their ID, and you will be asked to specify the ID of the item you want to restore.

External filesystems

The moving is actually performed by renaming the file, which is a lot faster than moving data around and gives exactly the same result. But, for external filesystems, sending an item to the trash means it must be moved, which can be quite slow.

On Windows, deleting an item from a NTFS device will send it to a device-specific recycle bin located in this drive and handled by Windows itself.

As Trasher only takes the trash directory it has been provided, you can use a device-specific trash by simply providing a trash directory path that is on the device you're removing items from.

But if you only want to use a single trash directory on, let's say, your computer's internal hard drive / SSD, removing items from an external storage device will fail by default. You can still allow it by providing the -m / --move-ext-filesystems option, which will make Trasher move the deleted items to the main filesystem's trash, which can take a lot of time if there are many (especially large) files and/or directories to move around.

It's also possible to specify a size limit for external filesystems' items. This way, items won't be moved around if they are too large, making the command fail instead. Such size can be provided with -s / --size-limit-move-ext-filesystems using an integer or floating-point size suffixed by either B for bytes, K for kilobytes, M for megabytes, G for gigabytes, T for terabytes, P for petabytes and finally E for exabytes. It's also possible to add another B or iB which makes the following sizes all valid: 2.4M, 2.4MB, 2.4MiB.

Usage

All commands look like this:

trasher --trash-dir <trash directory> <action>

By default, the command will fail if the trash directory doesn't exist, you can provide the --create-trash-dir flag to create it automatically:

trasher --create-trash-dir --trashdir <trash directory> <action>
# OR:
trasher --ct --trashdir <trash directory> <action>

You can for instance put the trash in your home directory:

trasher -ct ~/.trasher <action>

Actions

There are several actions available:

• ls: list items in the trash, use -d / --details to get the size and content of items
• rm <path>: move an item to the trash, use -p / --permanently to delete the item instead of moving it to the trash
• unrm <name>: restore an item in the current directory, use --id to provide an ID and --to to specify another restoration location
• drop <name>: permanently delete an item from the trash, use --id to provide an ID
• clear: remove all items from the trash

Technical details

Removed items' name must be UTF-8-compliant, so invalid UTF-8 filenames will make the program fail unless -a / --allow-invalid-utf8-item-names flag is provided during deletion, which will result in converting the filename to a valid UTF-8 string lossily.

Trash item's name is composed of the original item's name, its removal date and exact time in nanoseconds with timezone, as well as an ID which is a CRC on 24 bits of the deletion date.

CRC has been chosen as it's extremely fast and there's extremely low risks of collision between two different dates with a CRC on 24 bits (unless an item with the same name is deleted hundreds of thousands of times).

When removing an item, if multiple trash items have the same name, the ID is required along with the name, so the filename doesn't need to be CRC-ed and so we avoid all risks of collisions with filenames, which can have an enormous number of different values.