Search and replace text within multiple files

Question

I am migrating my blog, and all the posts have metadata at the top of the file. As a result I have a group of nearly 100 files in a directory where I want to do a search and replace for:

^permalink: http://blog.olddomain.com/(.*)$

to

permalink: http://blog.newdomain.com/$1

in all 100 files.

What commands would I use to do this?

Answer 1

sed is often used to pipe something through it, but it can process files just as well and, with the -i option, can even change them in place.

sed -i 's|^\(permalink: http://blog\.\)olddomain\(\.com/.*\)$|\1newdomain\2|g' <shell-glob-pattern>