“Add the option -f to fold upper and lower case together, so that case distinctions are not made during sorting; for example, a and A compare equal.”
Excerpt From: Brian W. Kernighan. “The C Programming Language, Second Edition.
I am not sure what this means exactly. I was thinking about two options:
- convert all uppercase to lowercase letters or vice versa
- keep the cases as they are and merely treat them as equal
Does the expression to fold something together in this case have a specific meaning?
Or am I free to choose an interpretation?