Transmission - ArchWiki

# Transmission

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

## Installation

There are several options in official repositories:

- transmission-cli - daemon, with CLI, and web client (http://localhost:9091) interfaces.
- transmission-remote-cli - Curses interface for the daemon.
- transmission-gtk - GTK3 package.
- transmission-qt - Qt5 package.

Note: 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.

## 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.

## 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) the `transmission` service with systemctl will use the user set in #Choosing a user. Note that the name for the systemd service is `transmission`, not `transmission-daemon`.

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

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

    $ transmission-remote --exit

#### Autostart at boot

Enable the `transmission` daemon to run at system start, using systemd.

Note that the name for the systemd service is `transmission`, not `transmission-daemon`.

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:

    /etc/systemd/system/transmission.service.d/fixdep.conf

    [Unit]
    Requires=network.target

#### Run only while connected to network

##### Netctl

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.

    /etc/netctl/hooks/90-transmission.sh

    #!/bin/sh

    # 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
                in=0
                break
            fi
        done
        return $in
    }

    # The SSIDs for which we enable this.
    ssids=(
        "network_1"
        "network_2"
    )

    # 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
            "CONNECT"|"REESTABLISHED")
                # Need to wait, otherwise doesn't seem to bind to 9091.
                sleep 30
                runuser -u transmission transmission-daemon
                ;;
            *)
                killall transmission-daemon
                ;;
        esac
    fi

##### Wicd

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:

    /etc/wicd/scripts/postconnect/transmission

    #!/bin/bash

    /usr/bin/transmission-daemon

    /etc/wicd/scripts/predisconnect/transmission

    #!/bin/bash

    killall transmission-daemon

##### NetworkManager

This article or section needs expansion.

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:

    /etc/systemd/system/transmission.service.d/username.conf

    [Service]
    User=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.

#### 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 `/lib/systemd/system/transmission.service`.

## Troubleshooting

### 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:

    /etc/sysctl.d/60-net_buffer.conf

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

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

## See also

- Transmission wiki
- HeadlessUsage

Category:

- Internet applications