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Transmission is a light-weight and cross-platform BitTorrent client. It is the default BitTorrent client in many Linux distributions.


There are several options in official repositories:

  • The GTK client cannot connect to the daemon, so users wishing to use the daemon will need to consider using the Qt package for a GUI or the remote-cli package for a curses-based GUI.
  • You cannot connect to the daemon over IPv6.[1]

Configuring the GUI version

Both GUI versions, transmission-gtk and transmission-qt, can function autonomously without a formal back-end daemon.

GUI versions are configured to work out-of-the-box, but the user may wish to change some of the settings. The default path to the GUI configuration files is ~/.config/transmission.

A guide to configuration options can be found on the Transmission web site:

GTK+ temporary cosmetic fix

With GTK+ 3.18, transmission-gtk shows black borders in random places; these can be hidden via gtk.css:

.tr-workarea .overshoot,
.tr-workarea .undershoot { border: none; }

Transmission daemon and CLI

The commands for transmission-cli are:

transmission-daemon: starts the daemon.
transmission-remote: invokes the CLI for the daemon, whether local or remote, followed by the command you want the daemon to execute.
transmission-remote-cli: (requires transmission-remote-cli) starts the curses interface for the daemon, whether local or remote.
transmission-cli: (deprecated) starts a non-daemonized local instance of transmission, for manually downloading a torrent.
transmission-show: returns information on a given torrent file.
transmission-create: creates a new torrent.
transmission-edit: add, delete, or replace a tracker's announce URL.

Starting and stopping the daemon

As explained in #Choosing a user, the transmission daemon can be run:

  • As the user transmission, by starting/enabling transmission.service using systemd.
you can change the user as explained in #Choosing a user
  • As your own user, by running under your user name:
    $ transmission-daemon
    The daemon can then be stopped with:
    $ killall transmission-daemon

Starting the daemon will create an initial transmission configuration file. See #Configuring the daemon.

An alternative option to stop transmission is to use the transmission-remote command:

$ transmission-remote --exit

Run only while connected to network


It may only be desirable to run transmission on certain networks. The following script checks that the connection is to a list of authorized networks and then proceeds to launch transmission-daemon.


# The SSIDs for which we enable this.
declare -A ssids=(

if [[ ${ssids[$SSID]} ]]; then
    case $ACTION in
            # Need to wait, otherwise doesn't seem to bind to 9091.
            sleep 30
            systemctl start transmission
            systemctl stop transmission


Create a start script in folder /etc/wicd/scripts/postconnect, and a stop script in folder /etc/wicd/scripts/predisconnect. Remember to make them executable. For example:


systemctl start transmission

systemctl stop transmission

Choosing a user

Choose how you want to run transmission:

  • As a separate user, transmission by default (recommended for increased security).

By default, transmission creates a user and a group transmission, with its home files at /var/lib/transmission/, and runs as this "user". This is a security precaution, so transmission, and its downloads, have no access to files outside of /var/lib/transmission/. Configuration, operation, and access to downloads needs to be done with "root" privileges (e.g. by using sudo).

  • Under the user's own user name.

To set this up, override the provided service file and specify your username:


Configuring the daemon

Create an initial configuration file by starting the daemon.

  • If running Transmission under the username transmission, the configuration file will be located at /var/lib/transmission/.config/transmission-daemon/settings.json.
  • If running Transmission under your own username, the configuration file will be located at ~/.config/transmission-daemon/settings.json.

One can customize the daemon by using a Transmission client or using the included web interface accessible via http://localhost:9091 in a supported browser.

A guide to configuration options can be found on the Transmission web site:

Note: If you want to edit the configuration manually using a text editor, stop the daemon first; otherwise, it would overwrite its configuration file when it closes.
Note: Alternatively, the daemon can be instructed to reload its configuration with SIGHUP, by running kill -s SIGHUP `pidof transmission-daemon`.

A recommendation for those running under username transmission is to create a shared download directory with the correct permissions to allow access to both the transmission user and system users, and then to update the configuration file accordingly. For example:

# mkdir /mnt/data/torrents
# chown -R facade:transmission /mnt/data/torrents
# chmod -R 775 /mnt/data/torrents

Now /mnt/data/torrents will be accessible for the system user facade and for the transmission group to which the transmission user belongs. Making the target directory world read/writable is highly discouraged (i.e. do not chmod the directory to 777). Instead, give individual users/groups appropriate permissions to the appropriate directories.

Note: If /mnt/data/torrents is located on a removable device, e.g. with an /etc/fstab entry with the option nofail, Transmission will complain that it cannot find your files. To remedy this, you can add RequiresMountsFor=/mnt/data/torrents to /etc/systemd/system/transmission.service.d/transmission.conf in the section [Unit].

An alternative is to add your user to the transmission group (#usermod -a -G transmission yourusername) and then modify the permissions on the /var/lib/transmission and /var/lib/transmission/Downloads directories to allow rwx access by members of the transmission group.

Watch dir

If you want to Automatically add .torrent files from a folder, but you find that the watch-dir and watch-dir-enabled options set in the config file do not work, you can start the transmission daemon with the flag -c /path/to/watch/dir.

If you're using systemd, edit the transmission.service unit as described in systemd#Editing provided units.

CLI Examples

If you want to remove all finished torrents you can use the following command with your own username and password

# transmission-remote -n 'username:password' -l | grep 100% | awk '{print $1}'| paste -d, -s | xargs -i transmission-remote -t {} -r


Cannot access the daemon over the network

The daemon is started after network.service was initialised. However, if you enable the service dhcpcd as opposed to the device-specific service, such as dhcpcd@enp1s0.service for example, it may happen that Transmission is started too early and cannot bind to the network interface. Thus, the web interface is unreachable. A possible solution is to add the Requires line to the unit's configuration file:


UDP Failed to set receive/sent buffer

The error messages UDP Failed to set receive buffer and UDP Failed to set sent buffer mean that Transmission would like a bigger sent and receive buffer. These buffers can be changed by adding the following file:


net.core.rmem_max = 16777216
net.core.wmem_max = 4194304

To load the new configuration run # sysctl --system and then reload Transmission.

See also