Chapter 3. Boot Process, Init, and Shutdown
59
S40atd  > ../init.d/atd
S45pcmcia  > ../init.d/pcmcia
S55sshd  > ../init.d/sshd
S56rawdevices  > ../init.d/rawdevices
S56xinetd  > ../init.d/xinetd
S60lpd  > ../init.d/lpd
S75keytable  > ../init.d/keytable
S80isdn  > ../init.d/isdn
S80sendmail  > ../init.d/sendmail
S85gpm  > ../init.d/gpm
S90canna  > ../init.d/canna
S90crond  > ../init.d/crond
S90FreeWnn  > ../init.d/FreeWnn
S90xfs  > ../init.d/xfs
S95anacron  > ../init.d/anacron
S95firstboot  > ../init.d/firstboot
S97rhnsd  > ../init.d/rhnsd
S99local  > ../rc.local
S99mdmonitor  > ../init.d/mdmonitor
As you can see, none of the scripts that actually start and stop the services are located in the
/etc/rc.d/rc5.d/
directory. Rather, all of the files in
/etc/rc.d/rc5.d/
are symbolic links
pointing to scripts located in the
/etc/rc.d/init.d/
directory. Symbolic links are used in each of
the
rc
directories so that the runlevels can be reconfigured by creating, modifying, and deleting the
symbolic links without affecting the actual scripts they reference.
The name of each symbolic link begin with either a
K
or an
S
. The
K
links are processes that are killed
on that runlevel, while those beginning with an
S
are started.
The
init
command first stops all of the
K
symbolic links in the directory by issuing the
/etc/rc.d/init.d/ command
stop
command, where
command
is the process to be
killed. It then starts all of the
S
symbolic links by issuing
/etc/rc.d/init.d/ command
start
.
Tip
After the system is finished booting, you can log in as root and execute these same scripts to start
and stop services. For instance, the command /etc/rc.d/init.d/httpd stop will stop the Apache
Web server.
Each of the symbolic links are numbered to dictate start order. You can change the order in which the
services are started or stopped by changing this number. Those symbolic links with the same number
are started alphabetically.
In the example
/etc/rc.d/rc5.d/
directory above, the
init
command will kill
pppoe
,
innd
,
ntpd
,
httpd
,
mysqld
,
pvmd
,
rarpd
,
bootparamd
,
nfs
,
rstatd
,
rusersd
,
rwalld
,
rwhod
,
squid
,
amd
,
mcserv
,
yppasswdd
,
dhcpd
,
smb
,
vncserver
,
arpwatch
,
named
,
snmpd
,
pxe
,
routed
,
mars nwe
,
ldap
,
kadmin
,
kprop
,
krb524
,
krb5kdc
,
gated
,
nscd
,
ypserv
,
ups
, and
irda
.
After all processes are killed,
init
looks into the same directory and finds start scripts for
kudzu
,
reconfig
,
ipchains
,
portmap
,
nfslock
,
autofs
,
random
,
netfs
,
apmd
,
identd
,
atd
,
pcmcia
,
sshd
,
rawdevices
,
xinetd
,
lpd
,
keytable
,
isdn
,
sendmail
,
gpm
,
canna
,
crond
,
FreeWnn
,
xfs
,
anacron
,
firstboot
,
rhnsd
, and
mdmonitor
.
The last thing the
init
program does is run any scripts located in
/etc/rc.d/rc.local
(see Sec 
tion 3.3 for more on customizing the
rc.local
file). At this point, the system is considered to be
operating at runlevel 5.






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