Unix System Administration Booting and Shutting Down Chapter 2

Six Steps to Better Footwear Sock Shoe, Sock Shoe or Sock Sock, Shoe, Shoe? Load and init the kernel Detect and config devices Create spontaneous processes Operator intervention System startup scripts Multi-user operation

Sock Shoe, Sock Shoe vs. Sock Sock, Shoe Shoe In case of fire... Sock sock, shoe shoe –Both feet will be kept warm Sock Shoe, Sock Shoe –If raining, sock sock will get wet and cold –Sock shoe can hop around on one foot to stay dry

Colonel Kernel Here! Let’s Go... Kernel is a program Path is vendor dependent –Solaris - /kernel/genunix –Linux - depends, sometimes /vmlinuz, see /etc/lilo.conf Two stage process –Boot loader read from disk or tape (vendor dependent) –Kernel loaded into memory

Let’s Probe Uranus Instead! Kernel’s first chore Detects and initializes devices built into kernel Probes for additional device info and other devices In Solaris, devices must be on and the system booted with boot -r to detect new devices

Processes That Start with a “(cheesy) Poof” BSD Spontaneous Processes –swapper - process 0 –init - process 1 –pagedaemon - process 2 ATT Spontaneous Processes –sched - process 0 –init - process 1 –various memory handlers (except on Solaris)

Hey, I Need a Little Help Here! Single-user mode Most modern version of Unix stop and ask for the “root” password before creating a Bourne shell with root privileges Minimal services running and partitions mounted Operator can run fsck, backups, etc. CTRL-D to proceed to multi-user startup

Just follow the Script Please Location, content and organization of the startup scripts varies by system Two “standard” startup script methods exist. BSD - /etc/rc, /etc/rc.boot, /etc/rc.single, /etc/rc.local ATT - /etc/inittab, /etc/rc*, /etc/rc*.d/, /etc/init.d

I’ll Go This Way, You Go the BSD Way

Ack. Kiptan. We’re heading into the SUN….

Calling All Operators, How Does ATT Startup? Run + /etc/inittab determines scripts to run /etc/rc* scripts run programs that start with “S” in the /etc/rc*.d directories –foreach f in rc2.d run $f /etc/rc*.d startup scripts are usually linked to a scripts in a common /etc/init.d directory

It’s More Fun in Multi-User Mode Multi-user mode is reached after all the startup scripts run The system is ready for more than one user to login at a time Services (e.g. web, nfs daemon, telnet daemon, ftp daemon) are up and waiting to service requests

Jeopardy Time Answer: The system won’t start. Answer: The startup script method Linux uses. Answer: It is the command used to properly shutdown the system.