Search notes:

Shell command: tr

tr translates or deletes characters.

tr can be used, for example to write each component (directory) of $PATH on a single line.

tr : '\n' <<<$PATH

Make all characters lower or upper case:

$ echo Hello World | tr '[:lower:]' '[:upper:]'
HELLO WORLD

$ echo Hello World | tr '[:upper:]' '[:lower:]'
hello world

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