O'Reilly logo

Expert Shell Scripting by Ron Peters

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

CHAPTER 3Date and Time Manipulation

On occasion, the need for date math arises, such as when you're trying to calculate a time interval between events. The calculations seem easy enough because there are precise numbers of seconds, minutes, and hours in a day. It gets tricky, though, when you consider the fact that values have to roll over when, for example, Monday turns into Tuesday or June becomes July.

For instance, calculating the difference in minutes between 6:53 am and 7:04 am is easy enough: you can multiply the hours (6 and 7) by 60 for each value, add the minutes that do not make up the next full hour, then subtract to find the difference. But what if you want the difference in minutes between 11:57 pm and 1:13 am? This calculation ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required