linux – bash中的错误 – 预期存在-e的一元运算符

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我想测试两个变量是否存在,在我使用“read”创建它之后.如果用户只输入我想要的两个变量之一,则会显示错误.

有我的代码：

while true;
do
  echo "Saisissez deux variables x et y sous la forme [x y]"
  read x y

  if [ !-e $x ] || [ !-e $y ] <<<<<< problem ligne
  then
    echo "Vous devez renseigner deux nombres x et y"
  elif [ $x = "." ]
  then
    exit 0
  else
    calcul $x $y
  fi
done

当我输入一个参数时出现错误：

[: !-e: unary operator expected

谢谢你的帮助 ：)

解决方法:

将其更改为：

if [ -z "$x" ] || [ -z "$y" ]

说明

> [实际上是一个内置的shell(尝试[或帮助[在你的提示];它是test的同义词.
> -z是[.的参数.它表示“测试下一个字符串的长度是否为0;如果是,则返回true;否则返回false.
>始终用双引号包装您正在测试的变量！

这是一个有用的选项列表[因为我认为你会感兴趣：

-b file = True if the file exists and is block special file. 
-c file = True if the file exists and is character special file. 
-d file = True if the file exists and is a directory. 
-e file = True if the file exists. 
-f file = True if the file exists and is a regular file 
-g file = True if the file exists and the set-group-id bit is set. 
-k file = True if the files "sticky" bit is set. 
-L file = True if the file exists and is a symbolic link. 
-p file = True if the file exists and is a named pipe. 
-r file = True if the file exists and is readable. 
-s file = True if the file exists and its size is greater than zero. 
-s file = True if the file exists and is a socket. 
-t fd = True if the file descriptor is opened on a terminal. 
-u file = True if the file exists and its set-user-id bit is set. 
-w file = True if the file exists and is writable. 
-x file = True if the file exists and is executable. 
-O file = True if the file exists and is owned by the effective user id. 
-G file = True if the file exists and is owned by the effective group id. 
file1 –nt file2 = True if file1 is newer, by modification date, than file2. 
file1 ot file2 = True if file1 is older than file2. 
file1 ef file2 = True if file1 and file2 have the same device and inode numbers. 
-z string = True if the length of the string is 0. 
-n string = True if the length of the string is non-zero. 
string1 = string2 = True if the strings are equal. 
string1 != string2 = True if the strings are not equal. 
!expr = True if the expr evaluates to false. 
expr1 –a expr2 = True if both expr1 and expr2 are true. 
expr1 –o expr2 = True is either expr1 or expr2 is true.

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