Meaning of the rcX.d files (rc3.d)
Files are linked from the /etc/rc.d/init.d/script location into the appropriate runlevel directory. Run levels are listed in /etc/inittab.
# Default runlevel. The runlevels used by RHS are: # 0 - halt (Do NOT set initdefault to this) # 1 - Single user mode # 2 - Multiuser, without NFS (The same as 3, if you do not have networking) # 3 - Full multiuser mode # 4 - unused # 5 - X11 # 6 - reboot (Do NOT set initdefault to this) #
Basically, when RedHat boots up, it picks one of these directories (rc[runlevel].d) to decide which services to start (or stop – when switch runlevels).
The default runlevel is set in the /etc/inittab file.
If a file is linked with a S##name (eg S45sap), the script is run with a start command. If, on the other hand, the file is named wth a K45name format, the script is run with a stop command.