Cross-Compiled Linux From Scratch - Version GIT-20170803-PowerPC

Chapter 7. If You Are Going to Boot

7.3. Boot-scripts for CLFS 3.0-20140710

The Boot-scripts package contains a set of scripts to start/stop the CLFS system at bootup/shutdown.

7.3.1. Installation of Boot-scripts

Install the package: 

make DESTDIR=/tools install-boot-scripts

The setclock script reads the time from the hardware clock, also known as the BIOS or the Complementary Metal Oxide Semiconductor (CMOS) clock. If the hardware clock is set to UTC, this script will convert the hardware clock's time to the local time using the /tools/etc/sysconfig/clock file (which tells the hwclock program which timezone the user is in). There is no way to detect whether or not the hardware clock is set to UTC, so this needs to be configured manually.

If you do not know whether or not the hardware clock is set to UTC, you can find out after you have booted the new machine by running the hwclock --localtime --show command, and if necessary editing the /tools/etc/sysconfig/clock file. The worst that will happen if you make a wrong guess here is that the time displayed will be wrong.

Change the value of the UTC variable below to a value of 0 (zero) if the hardware clock is not set to UTC time. 

cat > /tools/etc/sysconfig/clock << "EOF"
# Begin /tools/etc/sysconfig/clock

UTC=1

# End /tools/etc/sysconfig/clock
EOF

7.3.2. Contents of Boot-scripts

Installed scripts: checkfs, cleanfs, functions, halt, localnet, mountfs, mountkernfs, rc, reboot, sendsignals, setclock, swap, and udev.

Short Descriptions

checkfs

Checks the integrity of the file systems before they are mounted (with the exception of journal and network based file systems)

cleanfs

Removes files that should not be preserved between reboots, such as those in /run/ and /var/lock/; it re-creates /run/utmp and removes the possibly present /etc/nologin, /fastboot, and /forcefsck files

functions

Contains common functions, such as error and status checking, that are used by several boot-scripts

halt

Halts the system

localnet

Sets up the system's hostname and local loopback device

mountfs

Mounts all file systems, except ones that are marked noauto or are network based

mountkernfs

Mounts virtual kernel file systems, such as proc

rc

The master run-level control script; it is responsible for running all the other boot-scripts one-by-one, in a sequence determined by the name of the symbolic links being processed

reboot

Reboots the system

sendsignals

Makes sure every process is terminated before the system reboots or halts

setclock

Resets the kernel clock to local time in case the hardware clock is not set to UTC time

swap

Enables and disables swap files and partitions

udev

Starts and stops the Eudev daemon