Shell脚本使用if else来比较2个字符串

Question

我使用shell脚本来比较2个字符串变量是否为空白。并根据哪些变量为空白运行一些动作。

a=""
b=""

read a
read b

if [ -z $a ] && [ -n $b ] ;then
    echo "Var a is blank"
elif [ -n $a ] && [ -z $b ] ;then
    echo "Var b is blank"
elif [ -n $a ] && [ -n $b ] ; then
    echo "Both fields not empty"
else
    echo "Both fields are blank"
fi

如果我的字符串varibles有空格，我收到了if else语句的二元运算符预期错误。我究竟做错了什么？请帮忙。

Answer 1

您有语法错误。你可以用这个：

if [[ -z "$a" && -n "$b" ]]; then
    echo "a is empty"
elif [[ -n "$a" && -z "$b" ]]; then
    echo "b is empty"
elif  [[ -z "$a" && -z "$b" ]]; then
    echo "both are empty"
else
    echo "both are non-empty"
fi

Answer 2

始终双引号变量，如下所示：

if [ -z "$a" ] && [ -n "$b" ] ;then
...

这将保护字符串中的任何空格。