Learn Linux Shell Scripting - Fundamentals of Bash 4.4

Pattern substitution

Simply said, pattern substitution allows us to substitute a pattern with something else (who would have thought!). This is what we could already do with sed:

reader@ubuntu:~/scripts/chapter_16$ echo "Hi"Hireader@ubuntu:~/scripts/chapter_16$ echo "Hi" | sed 's/Hi/Bye/'Bye

Initially, our echo contains the word Hi. We then pipe it through sed, in which we look for the pattern Hi, which we will substitute with Bye. The s at the front of the instruction to sed signals that we're searching and replacing.

Behold, after sed is done parsing the stream, we end up with Bye on our screen.

If we want to do the same when using a variable, we have two options: we'll either parse it through sed as we did previously, or we'll turn to ...