6.1. init system
The file /etc/inittab contains the
background programs that used to keep the system running. One of
these programs is one getty process per
serial port.
Each field in inittab is separated by a
colon and contains:
- co
Arbitrary entry for inittab. As long
as this entry doesn't appear anywhere else in
inittab, you're okay. We named this entry
co because it's for the console.
Red Hat Linux
7.3 has a program called
kudzu which configures the system
when it is booted. kudzu treats an
inittab entry of co
specially, setting it for the attached monitor and keyboard or
the serial console. Hardcoding the value of
co prevents this behaviour.
- 2345
Run levels where this entry gets started. Run levels 2,
3, 4 and 5 can be used for an operational system,
getty should not be used in other run
levels. The serial console still works in run level 1 (or
single user mode) even without a
getty.
- respawn
Re-run the program if it dies. We want this to happen so
that a new login prompt will appear when you
log out of the console.
- /sbin/getty ttyS0 CON9600 vt102
The command to run. In this case, we're telling
getty to connect to /dev/ttyS0 using the settings for
CON9600 which exists in
/etc/gettydefs. This entry represents a
terminal running at 9600bps. Initially assume
that the terminal is a later-model
VT100.
After changing /etc/inittab restart
init with
An alternative is to send the hangup signal to
init with the command kill -HUP
1. This is not recommended: if you make a typing mistake
and actually kill init then your system
will suddenly halt.
 | Comments in inittab and Red Hat's
kudzu |
|---|
| | kudzu uses the
# line comment to activate and deactivate the
gettys for the attached monitor and
keyboard and for the serial port. To prevent a genuine comment
from becoming confused with a line saved by
kudzu use ## at the
start of a line of genuine comments. |
Take our 
