Admins-MacBook:MacOS shifttest$ export FOO=bar
Admins-MacBook:MacOS shifttest$ echo $FOO
bar
Admins-MacBook:MacOS shifttest$ echo ${FOO}
bar
Admins-MacBook:MacOS shifttest$ echo $(FOO)
-bash: FOO: command not found



$ brew install [email protected]
Error: No available formula with the name "[email protected]"
==> Searching for a previously deleted formula (in the last month)...
Error: No previously deleted formula found.
==> Searching for similarly named formulae...
Error: No similarly named formulae found.
==> Searching taps...
==> Searching taps on GitHub...
Error: No formulae found in taps.