Automatically launch your application
You've just developed a state of the art application and want it to be launched each time you boot your APF ? Then this small tutorial is for you !
First, a small remainder: when you start your board, here is how all things are started:
- U-Boot initializes the processor, vital peripherals and then load Linux image from Flash,
- U-Boot starts Linux image by passing it some parameters, the bootargs,
- Linux starts, mounts its rootfs and launches /sbin/init,
- init process checks its /etc/inittab config file and executes the instructions it contains,
- this config file generally asks init to launch /etc/init.d/rcS at some point,
- /etc/init.d/rcS look at all scripts in /etc/init.d/ directory which start with a S, and executes them in ascending order
Adding your own application in the system start process
- creates a shell script in /etc/init.d/:
# touch /etc/init.d/S99app # chmod a+x /etc/init.d/S99app
- edit it
# vi /etc/init.d/S99app
- put in it the following content (replace /usr/bin/your_app with your application name & path):
#!/bin/sh # Loading the modules needed by my app: modprobe xxxxx # Launching my app: /usr/bin/your_app & # <-- Don't forget the "&" otherwise other system stuff won't start until you leave your app !!! exit 0
- save your changes and !! Test it !!
- That's it ! You can now reboot:
# sync # reboot
Launching an application only on user login
- you may also prefer to launch your application only when a given user has logged in.
- indeed, after init has launched all the startup scripts, it generally gives the hand to getty and login tools that allow a user to login on the serial console or any other terminal.
- create a user account (here user test) and assign it a password:
$ adduser test Changing password for test New password: Retype password: Password for test changed by root
- leave root and log in as the new user:
$ exit Welcome to the Armadeus development environment. armadeus login: test Password: $ id uid=1001(test) gid=1001(test) groups=1001(test)
- /home/test/ directory was automatically created. Add the instructions to execute in the /home/test/.profile file:
$ cat > /home/test/.profile <<EOF echo "You just logged in !!" EOF