Editing on the Fly
Our experience with text editors has been largely interactive, meaning that we manually move a cursor around and then type our changes. However, there are non-interactive ways to edit text as well. It’s possible, for example, to apply a set of changes to multiple files with a single command.
tr—Transliterate or Delete Characters
tr program is used to transliterate characters. We can think of this as a sort of character-based search-and-replace operation. Transliteration is the process of changing characters from one alphabet to another. For example, converting characters from lowercase to uppercase is transliteration. We can perform such a conversion with
tr as follows:
echo "lowercase letters" | tr a-z A-Z ...