Korn Shell Programming by Example

Filters

We are often called on to filter the barrage of visual input we face every day. Depending on your nature, you might have filtered out the view of most of the oddly shaped and sized folks at the public beach last summer. After this filtering, you were left with a few choice items upon which you wanted to spend some processing time.

The Korn Shell provides many mechanisms for filtering data. You probably recognize some of these mechanisms as commands you use everyday. But most likely you don't usually consider the fact that the following are all filters: head, tail, grep, awk, sed, wc, tr, sort, uniq, more, cat, and so on.

What is the common thread that binds the previous list together as filters? They all expect their input from standard ...