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→Q: How to run automatically run applications on startup?
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==Introduction==
[http://en.wikipedia.org/wiki/Embedded_linux By definition] Embedded Linux is just a particular use of the well-known GNU/Linux duo. So most of documentation about GNU/Linux is meaningful for embedded Linux systems too. However, embedded Linux systems have some peculiarities you will not find on a desktop PC. This page aims to provide useful links and information about these issues. It also includes a [[#FAQs|section]] related to frequently asked questions that have a general validity across different embedded Linux platforms.
==Books==
Please refer to the [[Running Ubuntu Core]] page to learn how to run an Ubuntu-based root file system for ARM architecture.
==FAQs==
=== Q: How to run automatically run applications on startup? ===
'''A''': Generally speaking, several initialization systems are available on Linux platforms. By default, reference root file systems provided by DAVE Embedded Systems make use of ''System V init'' scripts. As such, user space application/services are automatically launched at boot time by the <code>Init</code> process (http://en.wikipedia.org/wiki/Init).
<code>Init</code> is configured customizing the <code>/etc/inittab</code> file and all the related scripts/links contained in the <code>/etc/init.d</code> and <code>/etc/rc*.d</code> directories. The system starts with a default runlevel (es: 5) and launches all the scripts contained in <code>/etc/rcX.d/</code> (with X matching the runlevel), which are symbolic links to the scripts stored in <code>/etc/init.d</code>.
It is advised to take advantage of this mechanism, creating and putting in place the scripts that launch your application.
It is also possible to invoke the scripts directly from the <code>/etc/inittab</code> file but this approach is discouraged.
For detailed information, please refer to the following links:
*http://www.tldp.org/LDP/intro-linux/html/sect_04_02.html
*http://www.tldp.org/LDP/sag/html/config-init.html
*http://www.linux-tutorial.info/modules.php?name=ManPage&sec=7&manpage=init.d
*http://www.yolinux.com/TUTORIALS/LinuxTutorialInitProcess.html.
It is worth remembering that if Yocto build system is used to generate the root file system, different initialization schemes may be chosen, such as <code>systemd</code>.