Using sed

In addition to our discussion about manipulating text, we absolutely must discuss sed. It's a go-to tool to solve so many problems where quick solutions are needed and a lot of text is involved. I can list more than a few examples just from the past couple of years where it saved my skin. For example, I had a couple of projects that required migrating WordPress sites from one domain to another. As it was something that needed to be done in a flash, testing migration modules wasn't an option. The simpler way was to just export the MySQL database, change domain1 to domain2, and check whether it worked. Later, I had a couple more projects like that where it wasn't just a domain name change; subdomain name changes were needed too, and so on. Keeping in mind that it would take me weeks to do this manually on a database that was gigabytes in size – yes, sed really helped me out in those jams. Let's discuss the merits of using sed and learn by working...