Shell Programming and Scripting

And some more ...

4. An Oracle DBA can set up scripts that write messages to alert logs, which basically are files in the underlying OS. Let's say you have just one log file with each message preceded by the date and timestamp. Maybe one day, you want to find out who all logged on yesterday, or last weekend or last month.

5. A web server like Apache may write messages at different times, to the same log file. And you may want to find out all messages written at an earlier date.

6. Consider an online shopping cart. You order a book at Amazon.com, for example. It shows you an expected date of delivery. There again you have a need to find out a future date, maybe based on an algorithm.

7. When you pay your credit cart online, you usually see the date when the amount will be debited from your bank account. It could be next day or the next business day (if the next day's a weekend, for instance). So there's the need to find out a future date.

8. If we are talking about the need to access later or earlier dates, then you'll find many examples in the world of databases.

In case of data warehouses for example, searching for information on previous date or time intervals is a very common activity. A manager may want to know the sales of last month, last year etc.

In case of Decision Support Systems (DSS), you may need to forecast certain things like sales, revenue, profits etc. based on the data of current and prior dates. Forecasting (or projection) could be for the next month, next year etc.

9. And there are many more...

You just need to observe the world around you, and you'll find them.

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