Networking and Booting

Network IV

This is a continuation of last Friday’s examples, theseries of servers, that echo JSON expressions.

Booting the computer

The file systems

Run the following commands on both your workstation and your Pi.

df -Th /
df -Th /boot
df -Th

Look at the Tecmint.com Linux Howto’s page on 7 Ways to Determine the File System Type in Linux and try these commands out on your Pi and workstation. You’ll have to skip the commands requiring sudo access on your workstation.

Initial Root Directory

This is a bit of an aside since it isn’t the first step in the boot process and often isn’t used in Raspberry Pi systems.

First, take a look at the Wikipedia page on the initial ramdisk. This file is stored in /boot/initrd.img-&hellip on the lab Ubuntu computers. On the Pi’s /boot/kernel7.img has a simular purpose, but it is difficult to decompress. So, we’re going to look at one on the workstations.

Some references

The present boot setup?

I just noticed that the latest version of the UNIX and Linux System Administration Handbook is available on-line at UNC Asheville. This has been consider the sysadmin book for years.

This is not all public domain software. There is (according to one source at Broadcom — yes, the one that’s in the news) there are million lines of protected code used to start the boot process. (See Understanding the Raspberry Pi Boot Process and boot flow for more details.

OS Running!

The first user process, init, or /sbin/init is started. Control passes to user space.

See what /sbin/init really is.

Systemd

It has won. However, there are still directores at /etc/rc*.d .

More on systemd