_test=`shasum -a 256 my "file here.txt" | awk -F' ' '{print $1}'`

This works as expected. But the OCD in me wants to use something like


But because of the single quotes in the awk section, I'm getting a bad substitution error.

$ _test="${shasum -a 256 "my file here.txt" | awk -F' ' '{print $1}'}"
zsh: bad substitution
$ _test=${shasum -a 256 \"my file here.txt\" | awk -F\' \' \'{print $1}\'}
zsh: bad substitution

Any ideas on how to get it to work? Thanks


What you are doing with ${...} is called Parameter Expansion. This will expand parameters - in your case, a parameter called shasum -a 256 "my file here.txt" | awk -F' ' '{print $1}', but that's not a valid parameter name, as described in Parameters:

A name may be any sequence of alphanumeric characters and underscores, or the single characters ‘*’, ‘@’, ‘#’, ‘?’, ‘-’, ‘$’, or ‘!’

What you actually want is to run everything in ${...} and for that you need Command Substitution, which uses parentheses instead of curly braces:

↪ touch "my file here.txt"
↪ _test="$(shasum -a 256 "my file here.txt" | awk -F' ' '{print $1}')"
↪ echo $_test

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