Replace case-insensitive string in all folder files

Question

I'm trying to replace a string with another in all files in dir. Trying to use this command

 sed 's/foo/bar/' *

But it replaces foo and not fOo or Foo and others.

how to find "foo" case-INsensitively?

Answer 1

With some sed implementations like GNU's or FreeBSD's:

sed 's/foo/bar/i' ./*

The i makes what you need.

If your sed doesn't support that non-standard extension, you can always do:

sed 's/[fF][oO][oO]/bar/' ./*