Transfer files
================

.. _rsync: https://en.wikipedia.org/wiki/Rsync

.. warning::
   This kitten is currently experimental, use with care.

Transfer files to and from remote computers over the ``TTY`` device itself.
This means that file transfer works over nested SSH sessions, serial links,
etc. Anywhere you have a terminal device, you can transfer files.

.. image:: ../screenshots/transfer.png
   :alt: The transfer kitten at work

This kitten supports transferring entire directory trees, preserving soft and
hard links, file permissions, times, etc. It even supports the rsync_
protocol to transfer only changes to large files.

.. seealso:: See the :doc:`remote_file` kitten

.. note::
   This kitten (which practically means kitty) must be installed on the other
   machine as well. If that is not possible you can use the :doc:`remote_file`
   kitten instead. Or write your own script to use the underlying :doc:`file transfer
   protocol </file-transfer-protocol>`.

.. versionadded:: 0.24.0


Basic usage
---------------

In what follows, the *local computer* is the computer running this kitten and
the *remote computer* is the computer connected to the other end of the TTY pipe.

To send a file from the local computer to the remote computer, simply run::

    kitty +kitten transfer /path/to/local/file /path/to/destination/on/remote/computer

You will be prompted by kitty for confirmation on allowing the transfer, and if
you grant permission, the file will be copied.

Similarly, to get a file from the remote computer to the local computer, use
the :option:`kitty +kitten transfer --direction` option::

    kitty +kitten transfer --direction=receive /path/to/remote/file /path/to/destination/on/local/computer

Multiple files and even directories can be transferred::

    kitty +kitten transfer file1 dir1 destination/

Here :file:`file1` will be copied inside :file:`destination` and :file:`dir1`
will be recursively copied into :file:`destination`. Note the trailing slash on
:file:`destination`. This tells kitty the destination is a directory. While not
strictly necessary (kitty will infer the need for a destination directory from
the fact that you are copying multiple things) it is good practice to always
use a trailing slash when the destination is supposed to be a directory.

Also, when transferring multiple files/directories it is a good idea to
use the :option:`kitty +kitten transfer --confirm-paths` option which will give
you an opportunity to review and confirm the files that will be touched.


Avoiding the confirmation prompt
------------------------------------

Normally, when you start a file transfer kitty will prompt you for
confirmation. This is to ensure that hostile programs running on a remote
machine cannot read/write files on your computer without your permission.
If the remote machine is trusted and the connection between your computer
and the remote machine is secure, then you can disable the confirmation prompt
by:

#. Setting the :opt:`file_transfer_confirmation_bypass` option to some
   password.

#. When invoking the kitten use the :option:`kitty +kitten transfer --permissions-bypass`
   to supply the password you set in step one.

.. warning:: Using a password to bypass confirmation means any software running
   on the remote machine could potentially learn that password and use it to
   gain full access to your computer. Also anyone that can intercept the data
   stream between your computer and the remote machine can also learn this
   password. So use it only with secure connections to trusted computers.


Delta transfers
-----------------------------------

This kitten has the ability to use the rsync_ protocol to only transfer the
differences between files. To turn it on use the :option:`kitty +kitten
transfer --transmit-deltas` option. Note that this will actually be slower when
transferring small files because of round trip overhead, so use with care.


.. include:: ../generated/cli-kitten-transfer.rst
