Difference between revisions of "Transmission"

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m (Configuring the GUI version)
(Run only while connected to network: use systemd instead of launching crap directly)
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             # Need to wait, otherwise doesn't seem to bind to 9091.
             # Need to wait, otherwise doesn't seem to bind to 9091.
             sleep 30
             sleep 30
             runuser -u transmission transmission-daemon
             systemctl start transmission
             killall transmission-daemon
             systemctl stop transmission
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systemctl start transmission
killall transmission-daemon
systemctl stop transmission

Revision as of 09:44, 15 January 2016

zh-CN:Transmission 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: https://trac.transmissionbt.com/wiki/EditConfigFiles#Options.

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: 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 running as root:
    # transmission-daemon
    The daemon can then be stopped with:
    # killall transmission-daemon
  • As your own user, by running under your user name:
    $ transmission-daemon
    The daemon can then be stopped with:
    $ killall transmission-daemon
  • Starting (and stopping) transmission.service with systemctl will use the user set in #Choosing a user. Note that the name of the systemd service is transmission.service, not transmission-daemon.service.

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

Autostart at boot

Enable transmission.service using systemd.

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:


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.


# A simple function to check whether an array contains a value
function contains() {
    local array="$1[@]"
    local seeking=$2
    local in=1

    for element in "${!array}"; do
        if [[ $element == $seeking ]]; then
    return $in

# The SSIDs for which we enable this.

# In the following, `${array_name[(I)search]}` returns 0 if `array_name` does
# not contain `search`, or the index of the match (starting at 1).
if contains ssids "$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

Tango-view-fullscreen.pngThis article or section needs expansion.Tango-view-fullscreen.png

Reason: Todo (Discuss in Talk: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: https://trac.transmissionbt.com/wiki/EditConfigFiles#Options

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.

Logging daemon to logfile

too many tracker error messages in the syslog. logfile facility needed.

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 unit file located at /etc/systemd/system/transmission.service.


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