In the final example, the value of the HOME variable is tested to see if it is a directory using the -d unary operator.

在最后一个示例中，测试home变量的值，用单目操作符- d检查它是不是目录。

youdao

Directory assistance (operator).

目录辅助(操作员)。

youdao

Traffic on the cellular network was running between 50 percent and 100 percent above normal levels, and its directory assistance and operator services were also overwhelmed, the company said in a statement.

CNN: Networks hit, but telecom stays operational