1. UNIX Startup and Shutdown CSCI N321 – System and Network Administration Copyright © 2000, 2009 by Scott Orr and the Trustees of Indiana University

2. Section Overview Bootstrapping Startup Scripts and Run Levels Boot Configuration and Troubleshooting System Shutdown

3. References CQU COIT13146 System Administration Course Textbook  Chapter 13 Chapter 13 Lectures  2002 #12 2002 #12

4. Monolithic vs. Microkernels Source:http://en.wikipedia.org/wiki/Microkernel

5. Bootstrapping Starting the system Process of loading kernel into memory Boot Modes Normal Single User Rescue (on CD)

6. RedHat Boot Process BIOS LoginShell GRUB /etc/inittab Source: http://nmc.nchu.edu.tw/linux/Linux_boot.htm LinuxKernelinit /etc/rc.d/rc.sysinit/etc/rc.d/rc RL Specific /etc/inittab/etc/rc.d/rc3.d/etc/rc.d/rc5.d

7. Fedora Boot Process BIOS LoginShell GRUB /etc/inittab Source: http://nmc.nchu.edu.tw/linux/Linux_boot.htm LinuxKernelinit /etc/event.d/* RL Specific /etc/rc.d/rc3.d/etc/rc.d/rc5.d

8. Boot Process Load & initialize kernel Detect & configure devices Fork system processes (Stop if Single User mode) Run startup scripts Start multiuser operations

9. Boot Loader ROM loads boot program from disk Boot program finds/loads kernel Checks available memory Initializes kernel internal data structures GRand Unified Bootloader (GRUB) Can boot multiple OS Boot options can be edited at boot Linux Boot Loader (LILO) Can boot multiple OS Single User: linux single Rescue: linux rescue

10. /etc/grub.conf default=1 timeout=10 splashimage=(hd0,5)/boot/grub/splash.xpm.gz title Fedora Core - N321 (2.6.11-1.1369_FC4) root (hd0,5) kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/1 rhgb quiet initrd /boot/initrd-2.6.11-1.1369_FC4.img title Windows XP rootnoverify (hd0,0) chainloader +1 title Red Hat Enterprise WS (2.6.9-11.EL) rootnoverify (hd0,4) kernel /boot/vmlinuz-2.6.9-11.EL ro root=LABEL=/ rhgb quiet initrd /boot/initrd-2.6.9-11.EL.img

11. System Processes BSD Systems swapper – PID 0 init – PID 1 pagedaemon – PID 2 AT&T SVR4 sched – PID 0 (invisible under RedHat) init – PID 1 /etc/inittab

12. Startup Scripts Hostname Timezone Check the hard drives Mount the hard drives Remove files from /tmp Configure network interfaces Start daemons and network services

13. BSD /etc/rc* Scripts /etc/rc Master script Executes supplemental scripts Example supplemental scripts (freeBSD) /etc/defaults/rc.conf /etc/rc.conf /etc/rc.conf.local

14. /etc/inittab Initializes system for use Format: id:rl:action:process id : uniquely identifies entry rl : Run level entry applies to action : How to execute process process : process command line Ex: Setting the default Runlevel: id:3:initdefault:

15. Startup Run Levels SolarisRedHatMode 1 (S) Single user 22Multiuser (no networking) 33Full Multiuser 44Unused 5Power-off shutdown 5X11 66Reboot 00Halt

16. Event file directives exec script start on stop on daemon respawn service

17. “Events” control-alt-delete power-status-changed startup runlevel started stopped

18. Virtual Consoles Started in /etc/event.d/tty[1-6] : Example (tty2): start on stopped rc2 start on stopped rc3 start on stopped rc4 start on started prefdm stop on runlevel 0 stop on runlevel 1 stop on runlevel 6 respawn exec /sbin/mingetty tty2

19. Started in /etc/event.d/rc[0-6,S] : Example (rc3): start on runlevel 3 stop on runlevel [!3] console output script set $(runlevel --set 3 || true) if [ "$1" != "unknown" ]; then PREVLEVEL=$1 RUNLEVEL=$2 export PREVLEVEL RUNLEVEL fi exec /etc/rc.d/rc 3 end script Strarting/Stopping Run Levels

20. Run Level Scripts Actual scripts - /etc/rc.d/init.d/ /etc/rc.d/rc#.d/ Symbolic links to /etc/init.d scripts S## - Start scripts K## - Stop scripts /etc/sysconfig/ - script configuration files chkconfig on|off service start|stop|restart

21. Startup Messages Displayed to console RedHat – daemon [ ok ] /bin/dmesg History of boot messages Convenient to search RedHat allows for interactive setup (“i”)

22. System Shutdown Turn off power – BAD!!! Reboot reboot shutdown –r Halting the system halt shutdown –h Changing the Run Level telinit shutdown –i

23. When to Shutdown Failures Maintenance and Upgrades Regularly Scheduled Housecleaning Window for Maintenance/Upgrades User Notification /etc/motd Email Support web pages