# Xpra

From the Xpra website:

Xpra is 'screen for X': it allows you to run X programs, usually on a remote host, direct their display to your local machine, and then to disconnect from these programs and reconnect from the same or another machine, without losing any state. It gives you remote access to individual applications.

- Xpra is "rootless" or "seamless": programs you run under it show up on your desktop as regular programs, managed by your regular window manager.
- Sessions can be accessed over SSH, or password protected over plain TCP sockets.
- Xpra is usable over reasonably slow links and does its best to adapt to changing network bandwidth limits. (see also adaptive JPEG mode)
- Xpra is open-source (GPLv2+), multi-platform and multi-language, with current clients written in Python and Java.

## Installation

Install the package xpra-winswitchAUR from the AUR, in the server and client(s) machines.

Tip: If you intend to run Xpra locally under a existing Xorg session with graphic drivers such as `nvidia` or `ATi` you will need to modify the default xpra config. Xpra fetches `-configdir` from `xorg-server-xvfb` which will be `/etc/X11/xorg.conf.d`, there for you need to change this by following the three bottom steps of 1333056#p1333056 in order to run xpra locally.

## Use

Start an xpra server on the machine where you want to run the applications (we are using display number 7 here):

    $ xpra start :7

Now you can start an application, e.g. firefox:

    $ DISPLAY=:7 firefox

Or, if you want to start a screen session and execute the programs from there to be able to close the console:

    $ DISPLAY=:7 screen
    [screen starts]
    $ firefox

Note that if you start `screen` like this you don't have to specify the display number when executing programs. They will be running on the xpra display automatically.

After running these commands, you don't see any windows yet. To actually see the applications on your display, you have to connect to the xpra server. If you are connecting to an xpra display on the same machine, start the xpra client like this:

    $ xpra attach :7

Or, if you are connecting to a remote machine over ssh:

    $ xpra attach ssh:user@example.com:7

After starting the client, any programs running on the remote server display are displayed on your local screen. To detach, type `ctrl-c` or use the command:

    $ xpra detach ssh:user@example.com:7

Programs continue to run on the server and you can reattach again later.

You can stop the server with:

    $ xpra stop :7

on the machine where the server is running, or remotely:

    $ xpra stop ssh:user@example.com:7

For a complete manual, check `man xpra`.

## Tips and tricks

### Start at boot

#### Server

It is possible to start the xpra server at boot using a systemd unit.

Create the unit file:

    /etc/systemd/system/xpra@.service

    [Unit]
    Description=xpra display

    [Service]
    Type=simple
    User=%i
    EnvironmentFile=/etc/conf.d/xpra
    ExecStart=/usr/bin/xpra --no-daemon start ${%i}

    [Install]
    WantedBy=multi-user.target

Now create the configuration, adding a line for each username you want to have an xpra display:

    /etc/conf.d/xpra

    myusername=:7

Enable the service for each username that owns a display. In this example, the service would be `xpra@myusername.service`.

#### Client

Note: If the client is a remote machine, first of all use SSH keys to be able to connect to the server without typing a password. Read SSH keys for more details.

##### Method 1: .xinitrc

Add to your `~/.xinitrc` file the line necessary to start the connection, adding an & at the end of the line.

Make sure to add such line before the `exec` line.

For example, on a remote client it could be:

    ~/.xinitrc

    xpra attach ssh:user@example.com:7 &

##### Method 2: systemd user session

Configure your session to use systemd user session. Read Systemd/User for details.

Note: Make sure you understand the difference between systemd user session services, and regular systemd services. Again, read the Systemd/User for details.

Create the following service unit:

    $HOME/.config/systemd/user/xpra-client@.service

    [Unit]
    Description=xpra client

    [Service]
    Type=simple
    EnvironmentFile=%h/.config/conf/xpra_client
    ExecStart=/usr/bin/xpra attach %i $OPTS

    [Install]
    WantedBy=default.target

Create the configuration file, using the options you want:

    $HOME/.config/conf/xpra_client

    OPTS=--encoding=jpeg --quality=90

The service name would be in the format of `xpra-client@ssh:username@hostname:<display number>.service`.

Example:

    xpra-client@ssh:myuser@example.com:7.service

Enable that service, and remember to use the `--user` flag on `systemctl`.

### Error: Only console users are allowed to run the X server

If the execution fails with this error message in the log file you need to make the following changes:

Create the file /etc/X11/Xwrapper.config with the content

    /etc/X11/Xwrapper.config

    allowed_users=anybody

## See also

- Xpra website

Category:

- X server