Fedora Linux

2. Start vi with the /boot/grub/grub.conf :

3. # vi /boot/grub/grub.conf
4.

5. The file will look something like this:

6. # grub.conf generated by anaconda
7. #
8. # Note that you do not have to rerun grub after making changes to this file
9. # NOTICE: You have a /boot partition. This means that
10. # all kernel and initrd paths are relative to /boot/, eg.
11. # root (hd0,1)
12. # kernel /vmlinuz-version ro root=/dev/Main/root
13. # initrd /initrd-version.img
14. #boot=/dev/hdc
15. default=0
16. timeout=5
17. splashimage=(hd0,1)/grub/splash.xpm.gz
18. hiddenmenu
19. title Fedora Core (2.6.17-1.2517.fc6)
20. root (hd0,1)
21. kernel /vmlinuz-2.6.17-1.2517.fc6 ro root=/dev/Main/root rhgb quiet
22. initrd /initrd-2.6.17-1.2517.fc6.img
23. title Windows XP
24. rootnoverify (hd0,0)
25. chainloader +1

26. This example shows two Fedora Core entries for two different kernel versions. There may be additional entries for other operating systems (such as Windows) or additional kernels.

27. Find a Fedora Core entry (the bold lines in the example above) usually, the one with the latest kernel. Make an identical copy of it immediately after the original location in the file:

28. title Fedora Core (2.6.17-1.2517.fc6)
29. root (hd0,1)
30. kernel /vmlinuz-2.6.17-1.2517.fc6 ro root=/dev/Main/root rhgb quiet
31. initrd /initrd-2.6.17-1.2517.fc6.img
32. title Fedora Core (2.6.17-1.2517.fc6)
33. root (hd0,1)
34. kernel /vmlinuz-2.6.17-1.2517.fc6 ro root=/dev/Main/root rhgb quiet
35. initrd /initrd-2.6.17-1.2517.fc6.img
36. Change the description of the copied section to indicate the runlevel that will be used:
37. title Fedora Core (2.6.17-1.2517_fc6) - Runlevel 3 - Character mode
38.

39. On the kernel line, append the runlevel that you wish to use (this will override the default runlevel in /etc/inittab ):

kernel /vmlinuz-2.6.17-1.2517.fc6 ro root=/dev/Main/root rhgb quiet 3

1. Optionally, change the default , timeout , or hiddenmenu options to suit your tastes.

2. The default option specifies which of the menu entries is booted by default; the menu entries are numbered starting at 0 , so you could set this line to 1 to boot the second item on the menu automatically:

3. default= 1
4.

5. The timeout option sets the number of seconds that the menu will be displayed before the default option is automatically chosen. To give the user 30 seconds to decide which boot option to use, change the timeout line to read:

6. timeout= 30
7.

8. hiddenmenu hides the menu until the user presses a key; remove the hiddenmenu line to automatically reveal the menu every time the system is booted.

9. Save the file and exit vi . The new menu option will appear the next time you boot the system.

4.5.2. How Does It Work?

Once the kernel has fully started up, it runs just one program: init . All other software is started directly or indirectly by init .

If a runlevel is specified in the kernel boot options, init uses that value for the runlevel; otherwise, it obtains a runlevel from the initdefault line in /etc/inittab .

init then looks for a sysinit enTRy in /etc/inittab and executes the command specified:

si::sysinit:/etc/rc.d/rc.sysinit

This executes the /etc/rc.d/rc.sysinit script, which performs some basic system setup common to all runlevels.

Next, init examines the /etc/inittab file, looking for entries that contain the current runlevel in the second field and wait or respawn in the third field. For runlevel 3, it will find these lines:

l3:3:wait:/etc/rc.d/rc 3
1:2345:respawn:/sbin/mingetty tty1
2:2345:respawn:/sbin/mingetty tty2
3:2345:respawn:/sbin/mingetty tty3
4:2345:respawn:/sbin/mingetty tty4
5:2345:respawn:/sbin/mingetty tty5
6:2345:respawn:/sbin/mingetty tty6

The first line starts the script /etc/rc.d/rc with the argument 3 . This in turn sequentially executes every script in /etc/rc.d/rc3.d that starts with the letter S (for start ); this is how runlevel-specific software and services get started. Scripts in that same directory that start with K (for Kill ) are used to stop software when switching from the runlevel.