Changing case

You can have a variable expand into its value with all characters uppercase or lowercase using the "${myvar^^}" and "${myvar,,}" forms, respectively:

bash$ fn='mixedCase'
bash$ printf '%s\n' "${fn^^}"
MIXEDCASE
bash$ printf '%s\n' "${fn,,}"
mixedcase
Can you guess what the form with a single ^ or  , might do, rather than a double one? Try it out.

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