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I want to set up my Raspberry Pi in a sort of "kiosk" mode where it boots up into a single full screen application. I know my way around the command line, but am a novice when it comes to customizing linux boot behavior. I am building the application and am planning to add the ability to safely shutdown the Raspberry Pi. What do I need to do in order to configure my Raspberry Pi to only run this one application?

Update: To be clear, I don't want to open a webpage. I also don't I want to change operating systems. I want to learn how to configure my operating system (Raspbian) to launch my own application instead of X (though my application may depend on X rendering in the background).

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I have never tried this, but since it seems you're still looking and haven't gotten an answer in almost a month, I'll tell you where I'd start.

This how-to is ancient, but the general outline seems sound. You don't have to do everything exactly the same. It does focus on using a web browser as the centerpiece but that is mostly irrelevant here (i.e., relax, it's not another "web-kiosk").

It refers to /etc/inittab, which most linux distros don't use anymore, but it so happens that debian wheezy (raspbian) does. The idea is you are going to use runlevel 4 as the kiosk and make it the default. You can do that or just use whatever is currently the default (2 or 3, I think). The raspbian I have running right now has been modified by me, so I am not sure what the original differences were between the /etc/rc[N].d directories -- which correspond to the 7 runlevels. You want to either use one that doesn't start the graphical login (lightdm) or else to remove lightdm from that runlevel. You might as well do that kind of thing the right way (see man update-rc.d).

Then, following this part of the how-to, you want to create your own boot service (aka. init) script for starting X and your app without a login. Don't do it quite that way, however; you need to conform to debian, so see /etc/init.d/README. Also, you don't have to use a window manager at all (although fvwm is still great, methinks particularly for this kind of thing, so keep it in mind if you do), because an .xinitrc like this:

#!/bin/sh

myApp

Will run just your app in plain X -- which is very very plain: no menus, no titlebars, no toolbars, etc, or a way for the user to start another application or get a shell. It just provides a cursor.

An issue with this is that if you go straight to a desktop from boot, that will be a superuser desktop. Actually, X instances always have a uid of 0, but the applications run from the xinitrc run as the user that started X -- in this case X was started by init, so the user will be root (although technically root is not logged in). Hence the above xinitrc would be better with:

su -c myApp pi

Which will run your app as the pi user instead (who is also technically not logged in).

Since technically no one is logged in, even if the kiosk user kills X (e.g. via ctrl-alt-delete) they will just be left at a login prompt. The how-to goes beyond that such that the service init script starts X (see NOTE below) in the foreground so that when it exits, the service script continues and runs shutdown -r now.

Remember that someone who has physical access to a (normal) machine can always circumvent whatever security you implement, so all you are really trying to do here is not make it too easy and to prevent nasty accidents.

Also remember that since your boot service will be doing this in the foreground, no other services will run after it, so make sure it is the absolute last one. Very important! You could, in fact, use /etc/rc.local instead, since that is normally guaranteed to be last ;) That will save you some time.

NOTE: Actually in the how-to it's another script, /root/kiosk, from this section. Notice that's just one line which references the .xinitrc script shown in the section above (3.4). Just put a line like that in your boot script directly. Your (preliminary) xinitrc, as already described, will be much simpler.


An Alternative to Staying Foregrounded with init...

The purpose of leaving the X invocation foregrounded is just to block the execution of the init script until X exits, so that the next line in the script (shutdown) will run:

startx
shutdown -r now

Here I've used startx instead of the how-to's /usr/X11R6/bin/xinit /root/kiosk.xinitrc .... line. This will use $HOME/.xinitrc, and $HOME would be /root. Pretty sure startx is also a blocking call, so until X exits, shutdown won't run. If instead you did this:

startx &
shutdown -r now

X would run, but then shutdown would run too, right away (obviously pointless).

You don't have to use that trick if you don't care about having shutdown come in -- as mentioned the user will just end up with a login prompt. But it does seem like a useful idea, since then you can just turn it off with ctrl-alt-backspace. Another idea, if your app is closeable, would be to use startx & in the init script, which backgrounds it and allows init to continue normally (this is fine; X will still be running and have control of the display -- "backgrounded" is a maybe a confusing term). Instead of in the init script, put shutdown in the xinitrc instead:

#!/bin/sh
#/root/.xinitrc

su -c myApp pi
shutdown -r now

Same trick, different place. Now when someone closes myApp, shutdown will happen (but if they kill X, it won't). You could also do it both ways, but I actually like this one better because it means you can exit X and get a login, which may be useful sometimes, and you can also easily turn the system off from the GUI.

Don't background (&) myApp in the .xinitrc even if there is no shutdown after it though, because when the .xinitrc is done X exits ;) The last call there has to persist in the foreground (normally, it's a DE or window manager).

Init scripts and .xinitrc are similar concepts. One is run by init, which is process 1 on linux (it's the only process started by the kernel). The other is run by the X server. Note that there are .xinitrc files and an xinitrc command (they're related but not the same).

  • If Raspbian uses /etc/inittab but most others don't anymore, what do they use instead? – Andrew Sep 20 '13 at 20:04
  • So if I want to allow ssh access while my app is running in the foreground, I need to make sure my .xinitrc script runs after that, correct? – Andrew Sep 20 '13 at 20:09
  • Debian uses a "sysV"-ish init system, and inittab is part of all that. More common init daemons now are systemd and upstart. – goldilocks Sep 20 '13 at 20:20
  • WRT your app running in the foreground, this is just because (sysV) init waits for those scipts to return before it starts the next one. So normally in an init script, if you are starting a persistent service, you background (aka. fork) it via &. Then the script itself exits, but the "backgrounded" process continues. "Backgrounding" just refers to a chain of execution, not something about what appears on the screen -- you could background your X invocation (lightdm must be backgrounded)...I'll edit something in about this. – goldilocks Sep 20 '13 at 20:22
  • WRT ssh, the ssh service (linked in /etc/rc[N].d) should start before yours, so that will be running ("in the background") to answer connections. It's still a multi-tasking system ;) – goldilocks Sep 20 '13 at 20:23
2

Look at this 'Digital Signage' project. It boots to GUI then opens a HTML5 powered browser. I'm not yet tried but i want to. Maybe you can put your application instead browser to boot full screen.

http://www.binaryemotions.com/raspberry-digital-signage/

  • Thanks for your answer, but that looks like a replacement for Raspbian that is configured to display a browser. I'd like to learn the steps to configure Raspbian how I want. – Andrew Aug 24 '13 at 20:44
  • There are no mention about Raspbian in your question. Try this. pikiosk.tumblr.com/post/38721623944/… – gurcanozturk Aug 24 '13 at 21:45
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Mentioned Raspberry Digital Signage is an operating system which displays a full-screen view restricted to the web page or slideshow/video playlist specified with no way to escape but rebooting the machine.

It can in fact display both a web view (HTML/HTML5 pages display) and a multimedia view (image slideshow and video player). Web view has three different possible sub-views: Firefox, Chromium and Midori (with Gnash support).

Chrome and Midori experiences are feature of version 2.0.

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