Bash bad substitution with subshell and substring

Question

A contrived example... given

FOO=\"/foo/bar/baz\"

this works (in bash)

BAR=$(basename $FOO) # result is BAR=\"baz\"
BAZ=${BAR         


        

Answer 1

As others have said, the first parameter of ${} needs to be a variable name. But you can use another subshell to approximate what you're trying to do.

Instead of:

BAZ=${$(basename $FOO):0:1} # result is bad substitution

Use:

BAZ=$(_TMP=$(basename $FOO); echo ${_TMP:0:1}) # this works