Referindo-se a variáveis no bash

Question

Existe uma diferença quando as variáveis são referidas como $ variableName e $ {variableName} no bash?

    

Answer 1

De man bash :

The basic form of parameter expansion is ${parameter}. The value
of parameter is substituted. The braces are required when
parameter is a positional parameter with more than one digit, or
when parameter is followed by a character that is not to be
interpreted as part of its name.

Exemplos:

echo ${10}
foo=bar
echo ${foo}bar