The command [[ -n ${string} ]] is a conditional statement used in shell scripting. Here, [[ is a shell keyword used to evaluate conditions, -n is an operator used to check if a string is non-empty, and ${string} represents the variable you want to check. In this command, the condition -n ${string} is checking whether the variable string is non-empty. If the string is indeed non-empty, the command will return a true value or exit status 0. If the string is empty, the command will return a false value or a non-zero exit status. For example, consider the following script: ```bash

!/bin/bash string="Hello, world!" if [[ -n ${string} ]]; then

echo "The string is non-empty"

else echo "The string is empty" fi `` In this script, if the variablestring` is non-empty (as it is in this case), it will display "The string is non-empty".