It's called command substitution (posix specification) and it invokes a subshell. The command in the braces of $() or beween the backticks (``) is executed in a subshell and the output is then placed in the original command.
Unlike the backticks, the $(...) form can be nested. So you can use command substitution inside another substitution.
There are aso differences in escaping characters within the substitution. I prefer the $(...) form.
Best Answer
It's very similar to the backticks ``.
It's called command substitution (posix specification) and it invokes a subshell. The command in the braces of
$()or beween the backticks (``) is executed in a subshell and the output is then placed in the original command.Unlike the backticks, the
$(...)form can be nested. So you can use command substitution inside another substitution.There are aso differences in escaping characters within the substitution. I prefer the
$(...)form.