Learn Linux Shell Scripting - Fundamentals of Bash 4.4

sed, the stream editor

Since we're now fully familiar with regular expressions, search patterns, and (extended) grep, it's time to move to one of the most powerful tools in the GNU/Linux landscape: sed. The term is short for stream editor, and it does exactly what is implied: editing streams.

In this context, a stream can be a lot of things, but in general, it is text. This text may be found within a file, but can also be streamed from another process, such as a cat grep-file.txt | sed .... In that example, the output of the cat command (equal to the content of grep-file.txt) serves as input for the sed command.

We will look at both in-place file editing and stream editing in our examples.