After scanning all option args (that is, those prefixed by a hyphen), if it finds one more arg, it takes it to be the name of the input file and tries to open it for reading.
在扫描了所有的选项参数(也就是那些以连字符为前缀的参数)后,如果selpg发现还有一个参数,则它会接受该参数为输入文件的名称并尝试打开它以进行读取。
For -opt, the value of arg is used as the replacement value only if a value has been defined for all of the listed variables.
对于- opt,只有为列出的所有变量定义一个值时,才能将arg的值用作替换值。
For -neg, the value of arg is used as the replacement value only if a value has not been defined for all of the listed variables.
对于- neg,只有没有为所有列出的变量定义值时,才能将arg的值用作替换值。
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