How can I get bash/zsh to change some text from "foo.foo.foo" to "foo foo foo" with a script/alias?

You can use tr command to convert character.

% echo "foo.foo.foo" | tr '.' ' ' 
foo foo foo

Using pure bash:

bash-3.2$ a='a.a.a'
bash-3.2$ echo "${a/./ }"
a a.a
bash-3.2$ echo "${a//./ }"
a a a

You can make a function and add to the end of your ~/.bashrc, for example:

nodot() {  echo "$1" | sed 's/\./ /g' ; }

usage example:

$ nodot foo.foo.foo
foo foo foo

You can use this function in zsh too, just add to your ~/.zshrc instead.

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