Command Expressions

• Also have two forms.

• The backquote (back-tick) form is supported by all shells.
• Also supports the popular form derived from the Korn shell: $( ... ).

• The advantage of the new style is that it can more easily be nested, since no character inside the parentheses is treated in a special manner: escaping is not necessary.

declare -a files=($(ls $(echo $HOME)))

declare -a files=(`ls \`echo \$HOME\``)