If the character is an operator, pop two operands, perform the appropriate operation, and then push the result onto the stack.

如果字符是个操作符，弹出两个操作数，执行恰当操作，然后把结果压入堆栈。

youdao

The ? operator works in the shell, too, but is interpreted as ., or match any single character.

操作符在 Shell 中也可以工作，但是被解释为 .，即匹配任意单个字符。

youdao

If the character is an operator, pop operators until you reach an opening parenthesis, an operator of lower precedence, or a right associative symbol of equal precedence.

如果字符是个操作符，弹出(pop)操作符，直至遇见开括号(opening parenthesis)、优先级较低的操作符或者同一优先级的右结合符号。

youdao