sed for Not Yet Techies

sed is a powerful UNIX utility for editing text files. sed is especially useful for such functions as "search and replace" across many files. It is a non-interactive, stream-oriented editor.

sed uses pattern matching and has been available since the 7th version of the operating system, or UNIX V7.

It is available for download from the Free Software Foundation web site.

It evolved from the old line text editor, ed. Yes, I know that sounds like bad poetry but there it is.

Let's say you've just written a novel. Each chapter is a separate text file. After you've written Chapter 50, you decide to change the name of the main character.

You originally named your character Charlie Brown. Then you discover that is already the name of a famous comic strip character in Peanuts, and you don't want people thinking your character is a loser, so you decide to rename him Charles Atlas.

Any decent text editor today will have a search and replace function. But they normally don't cover multiple files at once. They apply to the file you happen to have open. So you would have to open up all 50 chapters, one file after another , and run Search and Replace on each separate chapter. It could take well over an hour and be very boring. I've done this with long works of my own.

Use sed to run Search and Replace on all 50 text files at once, and you're done. Charlie Brown is now Charles Atlas and none of your readers will ever know his original name.

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