如果使用shell脚本ELIF网络 [英] using if elif fi in shell scripts

问题描述

我不知道该怎么办了，如果在外壳多次测试，我无法写这个剧本：

I'm not sure how to do an if with multiple tests in shell, I'm having trouble writing this script:

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

问题是我每次收到此错误：./compare.sh：[：缺少`]命令未找到
谢谢！

the problem is I get this error every time: ./compare.sh: [: missing `]' command not found Thank you!

推荐答案

SH 是间preting的＆放大器;＆安培; 作为外壳运营商。将其更改为 -a ，这是的[配合运营商：

sh is interpreting the && as a shell operator. Change it to -a, that’s [’s conjunction operator:

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

此外，你应该总是引用变量，因为 [当你离开过争论变得迷茫。

Also, you should always quote the variables, because [ gets confused when you leave off arguments.

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