Oracle Shell Scripting Best Practices

Oracle Tips by Burleson Consulting
December 26, 2007

Question: What are the best practices for using OS shell scripts? I'm charged with managing all the oracle crontab entries on a 16-way Linux server, and we use a variety of shell like ksh, csh and bash. What are the best practices for using Oracle shell scripts?

Answer: There is an excellent overview of Oracle shell scripting best practices in book "Oracle Shell Scripting" by Jon Emmons, and see the book "Oracle Job Scheduling" for an overview of using dbms_scheduler for executing external shell scripts within Oracle.

See these important notes on color coding your prompt, OS prompt best practices, and making the prompt include the host name, instance name and current directory.

DBA's have been using cron jobs to schedule external Oracle jobs since the early 1990's, long before Oracle introduced their own job scheduling functionality (dbms_job and dbms_scheduler). External job include anything that interfaces with OS files such as:

Server-side monitoring (e.g. vmstat to Oracle capture scripts)
Alert log scanning
Trace and dump file management
Archived redo log management
Automated external batch jobs that interface with other OS utilities

The standards and best practices for shell scripting vary widely between shops, but in general they falls into these areas:

Shell script standards - It's always best to standardize on a shell. Historically, most shops used Korn shell (ksh), but today many shops use the Bourne Again shell (bash).
Job invocation best practices - After 10gr2 introduced secure external job scheduling with dbms_scheduler (with the create external job privilege), some shops abandoned cron-based jobs and moved everything into Oracle. One benefits of scheduling Oracle external tasks via dbms_scheduler is that the job is not "forgotten" if the system is down, as-is the case with crontab entries. Other shops use more sophisticated job scheduling software such as Appworx, where complex job dependencies exist.
Shell coding standards - All shell scripts should follow general coding best practices, including standardized reusable sub-shells for repetitive tasks (e.g. invoking SQL*Plus), and adhere to standards for coding style and comments. The best references on best practices for Oracle shell scripting in the outstanding book "Oracle Shell Scripting" by Jon Emmons.