Command substitution.

[VanYoshiko]

Is command substitution available.

echo $(date)
$(date)

echo date
date

[holzschu]

Short answer: not in the default shell, but you can launch dash, which is an almost complete sh shell (it's not bash, though) and has command substitution.

Long answer: the default shell is a simplified shell, designed to take as little as possible resources (and have simple code). Hence it has fewer functionalities. But if you need a full sh shell, you can start dash. And there's an option available in Settings where dash restarts automatically every time.