Symbolic link is defined like this (default runlevel is 5):
[root@PC003 rc5.d]# ls -l | grep oracle
lrwxrwxrwx 1 root root 19 Mar 14 17:03 81oracle -> /etc/init.d/dbstart
DBSTART script is located here:
[root@PC003 init.d]# ls -l | grep dbstart
-rwxr-xr-x 1 root root 4679 Mar 14 17:05 dbstart
[root@PC003 init.d]# pwd
When Linux is booting, message STARTING ORACLE shows OK response, but Oracle is not started automatically. I checked everything I could (links, case sensitive, runlevels etc), except the DBSTART script (that I found in $ORACLE_HOME/bin) because I don't understand it so deeply. I'm using Oracle 18.104.22.168.0 Standard for Intel Linux.