Unix - Cron Job Help

Up until now I used Oracle's Enterprise manager to submit the batch job. However its SMTP function (Sends EMail about Job status) is unstable lately. I want to use Unix's Cron to submit my batch job. This way I can also eliminate the middle layer (Oracle's Enterprise manager). Please help how I can do this...

This is what I want

----Job1
----Job2
--------Job3
------------Job4
----------------Job5

Means Job1 will start .Job1 fails or comples successfully I want Job 2 to start. After that all subsequent jobs are dependent on success of previous job. Means Job3 must start only if Job2 completes successfully.

Job3 depends on Success of Job2
If Job2 failes...whole cycles halts right there.

Job4 depends on Success of Job3
If Job3 failes...whole cycles halts right there.

Job5 depends on Success of Job4
If Job4 failes...whole cycles halts right there.

Once all this is done I want to send the emaiil along with the Job output.

All my jobs are nothing but submitting a OS COmmand

Example .
Job1 --

sqlplus -s user/password @/level1/scripts/data_flush.sql

Job2.

sqlplus -s user/password @/level1/scripts/data_load_step1.sql

So on and so forth...

Please help

Why do you need seperate jobs?

if <command>; then
  if <command>; then
    if <command>; then
      <command>
    fi
  fi
fi