Transfer files

Added in version 0.30.0.

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.

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.

See also

See the Remote files kitten

Basic usage

Simply ssh into a remote computer using the ssh kitten and run the this kitten (which the ssh kitten makes available for you on the remote computer automatically). Some illustrative examples are below. To copy a file from a remote computer:

<local computer>  $ kitten ssh my-remote-computer
<remote computer> $ kitten transfer some-file /path/on/local/computer

This, will copy some-file from the computer into which you have SSHed to your local computer at /path/on/local/computer. kitty will ask you for confirmation before allowing the transfer, so that the file transfer protocol cannot be abused to read/write files on your computer.

To copy a file from your local computer to the remote computer:

<local computer>  $ kitten ssh my-remote-computer
<remote computer> $ kitten transfer --direction=upload /path/on/local/computer remote-file

For more detailed usage examples, see the command line interface section below.


If you dont want to use the ssh kitten, you can install the kitten binary on the remote machine yourself, it is a standalone, statically compiled binary available from the kitty releases page. Or you can write your own script/program to use the underlying file transfer protocol.

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, then you can disable the confirmation prompt by:

  1. Setting the file_transfer_confirmation_bypass option to some password.

  2. When invoking the kitten use the --permissions-bypass to supply the password you set in step one.


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.

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 --transmit-deltas option. Note that this will actually be slower when transferring small files or on a very fast network, because of round trip overhead, so use with care.

Source code for transfer

The source code for this kitten is available on GitHub.

Command Line Interface

kitty +kitten transfer [options] source_files_or_directories destination_path

Transfer files over the TTY device. Can be used to send files between any two computers provided there is a TTY connection between them, such as over SSH. Supports copying files, directories (recursively), symlinks and hardlinks. Can even use an rsync like protocol to copy only changes between files. When copying multiple files, use the --confirm-paths option to see what exactly will be copied. The easiest way to use this kitten is to first ssh into the remote computer with the ssh kitten:

$ kitten ssh my-remote-computer

Then, on the remote computer run the transfer kitten to do your copying. To copy a file from the remote computer to the local computer, run:

$ kitten transfer remote-file /path/to/local-file

This will copy remote-file from the remote computer to /path/to/local-file on the local computer.

Similarly, to copy a file from the local computer to the remote one, run:

$ kitten transfer --direction=upload /path/to/local-file remote-file

This will copy /path/to/local-file from the local computer to remote-file on the remote computer.

Multiple files can be copied:

$ kitten transfer file1 file2 /path/to/dir/

This will put file1 and file2 into the directory /path/to/dir/ on the local computer.

Directories can also be copied, recursively:

$ kitten transfer dir1 /path/to/dir/

This will put dir1 and all its contents into /path/to/dir/ on the local computer.

Note that when copying multiple files or directories, the destination must be an existing directory on the receiving computer. Relative file paths are resolved with respect to the current directory on the computer running the kitten and the home directory on the other computer. It is a good idea to use the --confirm-paths command line flag to verify the kitten will copy the files you expect it to.


--direction <DIRECTION>, -d <DIRECTION>

Whether to send or receive files. send or download copy files from the computer on which the kitten is running (usually the remote computer) to the local computer. receive or upload copy files from the local computer to the remote computer. Default: download Choices: download, receive, send, upload

--mode <MODE>, -m <MODE>

How to interpret command line arguments. In mirror mode all arguments are assumed to be files/dirs on the sending computer and they are mirrored onto the receiving computer. Files under the HOME directory are copied to the HOME directory on the receiving computer even if the HOME directory is different. In normal mode the last argument is assumed to be a destination path on the receiving computer. The last argument must be an existing directory unless copying a single file. When it is a directory it should end with a trailing slash. Default: normal Choices: mirror, normal

--compress <COMPRESS>

Whether to compress data being sent. By default compression is enabled based on the type of file being sent. For files recognized as being already compressed, compression is turned off as it just wastes CPU cycles. Default: auto Choices: always, auto, never


The password to use to skip the transfer confirmation popup in kitty. Must match the password set for the file_transfer_confirmation_bypass option in kitty.conf. Note that leading and trailing whitespace is removed from the password. A password starting with ., / or ~ characters is assumed to be a file name to read the password from. A value of - means read the password from STDIN. A password that is purely a number less than 256 is assumed to be the number of a file descriptor from which to read the actual password.

--confirm-paths, -c

Before actually transferring files, show a mapping of local file names to remote file names and ask for confirmation.

--transmit-deltas, -x

If a file on the receiving side already exists, use the rsync algorithm to update it to match the file on the sending side, potentially saving lots of bandwidth and also automatically resuming partial transfers. Note that this will actually degrade performance on fast links or with small files, so use with care.