Learn to use the Sed text editor

Created for version 7 of AT[he]amp[/he]T’s original Unix operating system, the sed command has been included with probably every Unix and Linux OS since. The sed application is a stream editor, and unlike a text editor it doesn’t open a visual buffer into which a file’s data is loaded for processing. Instead, it operates on a file, line by line, according to either a command typed into a terminal or a series of commands in a script.