Метод 1. Использование операторов if, elif и else:

if [ condition1 ]; then
    # Code to execute if condition1 is true
elif [ condition2 ]; then
    # Code to execute if condition1 is false and condition2 is true
else
    # Code to execute if both condition1 and condition2 are false
fi

Метод 2. Использование операторов case:

case "$variable" in
    pattern1)
        # Code to execute if variable matches pattern1
        ;;
    pattern2)
        # Code to execute if variable matches pattern2
        ;;
    *)
        # Code to execute if variable doesn't match any patterns
        ;;
esac

Метод 3. Использование вложенных операторов if:

if [ condition1 ]; then
    # Code to execute if condition1 is true
    if [ condition2 ]; then
        # Code to execute if both condition1 and condition2 are true
    else
        # Code to execute if condition1 is true and condition2 is false
    fi
else
    # Code to execute if condition1 is false
fi