Question

我不确定如何在shell中进行多个测试if。我在编写这个脚本时遇到了麻烦：

echo "You have provided the following arguments $arg1 $arg2 $arg3"
if [ "$arg1" = "$arg2" && "$arg1" != "$arg3" ]
then
    echo "Two of the provided args are equal."
    exit 3
elif [ $arg1 = $arg2 && $arg1 = $arg3 ]
then
    echo "All of the specified args are equal"
    exit 0
else
    echo "All of the specified args are different"
    exit 4
fi

问题是我每次都会收到此错误：

./ compare.sh：[：missing`]'找不到命令

Answer 1

sh将&&解释为shell运算符。将其更改为-a，即[的合作运算符：

[ "$arg1" = "$arg2" -a "$arg1" != "$arg3" ]

另外，你应该总是引用变量，因为[在你离开参数时会感到困惑。

Answer 2

Josh Lee的回答有效，但您可以使用“＆amp;＆amp;”运算符为了更好的可读性，如下所示：

echo "You have provided the following arguments $arg1 $arg2 $arg3"
if [ "$arg1" = "$arg2" ] && [ "$arg1" != "$arg3" ]
then 
    echo "Two of the provided args are equal."
    exit 3
elif [ $arg1 = $arg2 ] && [ $arg1 = $arg3 ]
then
    echo "All of the specified args are equal"
    exit 0
else
    echo "All of the specified args are different"
    exit 4 
fi

Answer 3

使用双括号......

if [[ expression ]]

Answer 4

我的代码中有一个示例。试试这个：

echo "*Select Option:*"
echo "1 - script1"
echo "2 - script2"
echo "3 - script3 "
read option
echo "You have selected" $option"."
if [ $option="1" ]
then
    echo "1"
elif [ $option="2" ]
then
    echo "2"
    exit 0
elif [ $option="3" ]
then
    echo "3"
    exit 0
else
    echo "Please try again from given options only."
fi

这应该有效。：）

Answer 5

将“[”改为“[[”和“]”改为“]]”。

Answer 6

这对我有用，

 # cat checking.sh
 #!/bin/bash
 echo "You have provided the following arguments $arg1 $arg2 $arg3"
 if [ "$arg1" = "$arg2" ] && [ "$arg1" != "$arg3" ]
 then
     echo "Two of the provided args are equal."
     exit 3
 elif [ $arg1 == $arg2 ] && [ $arg1 = $arg3 ]
 then
     echo "All of the specified args are equal"
     exit 0
 else
     echo "All of the specified args are different"
     exit 4
 fi

 # ./checking.sh
 You have provided the following arguments
 All of the specified args are equal

您可以在脚本中添加“set -x”来解决错误，

感谢。

在shell脚本中使用if elif fi

6 个答案: