使用getopt（）查找目標

Question

所以我知道你可以使用getopt()來查找選項參數，但是argv數組中的其他內容如目標呢？有沒有辦法做到這一點使用getopt()？通過手冊頁看，我什麼也沒有看到......也許我錯過了它。

Answer 1

使用optarg表示（它是一個字符串，使用sscanf來讀取它）。

從man 3 getopt報價：

optstring is a string containing the legitimate option characters. If such a character is followed by a colon, the option requires an argument, so getopt() 
    places a pointer to the following text in the same argv-element, or the text of the following argv-element, in optarg. Two colons mean an option takes an 
    optional arg; if there is text in the current argv-element (i.e., in the same word as the option name itself, for example, "-oarg"), then it is returned in 
    optarg, otherwise optarg is set to zero. This is a GNU extension. If optstring contains W followed by a semicolon, then -W foo is treated as the long 
    option --foo. (The -W option is reserved by POSIX.2 for implementation extensions.) This behavior is a GNU extension, not available with libraries before 
    glibc 2. 

如果你有額外的參數（點菜cp -l file1 file2）它們保留在argv最新的位置，從optind。

PS：在man頁面末尾還有一個示例。