shell脚本报错:"[: =: unary operator expected" 在匹配字符串相等时,我用了类似这样的语句: if [ $STATUS == "OK" ]; then echo "OK" fi 究其原因,是因为如果变量STATUS值为空,那么就成了 [ = "OK"] ,显然 [ 和 "OK" 不相等并且缺少了 [ 符号,所以报了这样的错误。 当然不总是出错,如果变量...
One of the most common operators that you'll encounter is the simple assignment operator "=". You saw this operator in the Bicycle class; it assigns the value on its right to the operand on its left: int cadence = 0; int speed = 0; int gear = 1; This operator can also be used...
A definition of a unary operator specifies a parameter with a type other than that of the class or structure in which the operator is defined.When you define an operator in a class or structure, at least one of the parameters must be of the type of that class or structure. In the cas...
Learn how to use the Unary Minus operator in MySQL to negate numbers and understand its application in queries.
The unary operators operate on the object for which they were called and normally, this operator appears on the left side of the object, as in !obj, -obj, and ++obj but sometime they can be used as postfix as well like obj++ or obj--....
-ea operator -ErrorAction:SilentlyContinue parameter is not being respected & $error variable not updated -ExpandProperty & Export CSV !!! powershell script to add a word in the beginning of the text file - URGENT !!! 'A positional parameter cannot be found that accepts argument '$null'. ...