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https://github.com/spanezz/nodm

Automatic display manager
https://github.com/spanezz/nodm

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Automatic display manager

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README 

        
# THIS REPOSITORY IS NOT MAINTAINED



I do not use nodm anymore. I do not maintain nodm anymore.



To be really functional, nodm needs to be refactored to properly be a display

manager with all that it requires in 2019 to be one. It currently does not make

any effort to do so, and will break in obscure way as a result.



Nobody should really need nodm anymore: [lightdm's autologin now does the right

thing out of the box](https://www.enricozini.org/blog/2019/himblick/x-autologin/):

please use that.



If you are really attached to nodm, please consider maintaining it instead:

fork it, remove this section from the README, and turn it into a well done

reference implementation of a display manager without a GUI, that integrates

well with modern setups like lightdm does. I would applaud you for that!



# nodm



nodm is a minimal display manager that simply logs in as a given user and

starts an X session, without asking for username or password.



On a normal computer, using nodm is a big security issue because it would give

anyone access to the computer.



However, there are cases where automatic login is needed: for example in an

embedded system such as a mobile phone, or in a kiosk setup, or in a control

panel for industrial machinery.  For those cases, nodm is simple to setup,

lightweight, and it should do exactly the right thing.



## Features



nodm is as small as it could be, and tries to provide the minimum amount of

features needed to do a good job, following as much as possible the principle

of least surprise.  This is what is offered:



 - Automatic login with a fixed user, doing all that needs to be done like

   setting up the session via PAM, updating lastlog, logging to syslog.

 - nodm performs VT allocation, looking for a free virtual terminal in which to

   run X and keeping it allocated across X restarts.

 - X is started (by default, /usr/bin/X)

 - once the X esrver is ready to accept connections, the X session is set up:

    - the DISPLAY and WINDOWPATH environment variables are set

    - the session is wrapped in a PAM session, which sets up the user

      environment

    - ~/.xsession-error is truncated if it exists

 - The session script is run (by default, /etc/X11/Xsession) using "sh -l"

 - If the X server or the X session exit, the other is killed and then both are

   restarted.

 - If a session exits too soon, nodm will wait a bit before restarting.  The

   waiting times go as follow:

    - The first time the session exits too soon, restart immediately

    - The second and third time, wait 30 seconds

    - All remaining times, wait 1 minute.

   Once a session lasts long enough, the waiting time goes back to zero.



nodm does NOT currently fork and run in the background like a proper daemon:

most distributions have tools that do that, and nodm plays just fine with them.

This is not a particular design choice: quite simply, so far no one has felt

the need to implement it.



## Configuration



Configuration is made via these environment variables:



 * `NODM_USER`:

    Controls the user that is used to automatically log in.

 * `NODM_X_OPTIONS`:

    X server command line (for example: "vt7 -nolisten tcp").

    It is expanded using wordexp, with tilde expansion, variable substitution,

    arithmetic expansion, wildcard expansion and quote removal, but no command

    substitution. If command substitution is needed, please get in touch

    providing a real-life use case for it.



    If the first optiom starts with '/' or '.', it is used as the X server, else

    "X" is used as the server.



    If the second option (or the first if the first was not recognised as a path

    to the X server) looks like ":", it is used as the display name, else

    ":0" is used.



    If the command line contains a "vt" virtual terminal indicator, automatic

    VT allocation is switched off. Otherwise, the appropriate vt option is

    appended to the X command line according to the virtual terminal that has

    been allocated.

 * `NODM_MIN_SESSION_TIME`:

    Minimum time (in seconds) that a session should last in order for nodm to

    decide that it has not quit too soon. If an X session runs for less than

    this time, nodm will wait an increasing amount of time before restarting it

    (default: 60).

 * `NODM_XSESSION`:

    X session command (default: /etc/X11/Xsession). It is run using the shell, so

    it can be any shell command.

 * `NODM_XINIT`

    Was used by older versions of nodm as the path to the xinit program, but it

    is now ignored.

 * `NODM_X_TIMEOUT`

    Timeout (in seconds) to wait for X to be ready to accept connections. If X is

    not ready before this timeout, it is killed and restarted.