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professional perl programming wrox 2001 phần 6

Mô-đun fcntl xác định nhãn cho các lá cờ số, chẳng hạn như O_WRONLY chỉ ghi truy cập hoặc O_CREAT để tạo ra các tập tin nếu nó không tồn tại. Chế độ này không thể được kết hợp với tên tập tin với mở, thay vào đó nó đưa ra sau khi tên tập tin như là một tham số thứ ba bổ sung | Terminal Input and Output Simpo PDF Merge and Split Unregistered Version - http www.simpopdf.com This produces a list resembling but possibly not exactly the same depending on where and on what we run the program the following perl getcontrolchars.pl discaRd 15 EOF 4 EOL 0 EOL2 0 ERASE 127 ERASEWORD 23 INTERRUPT 3 KILL 21 MIN 1 QUIT 28 QUOTENEXT 22 REPRINT 18 START 17 STOP 19 SUSPEND 26 SWITCH 0 TIME 0 This list of operations and characters comes from the terminal and represents the internal mapping that it is using to process control characters. Many of the operations returned in the list may not be assigned and so have a character value of zero or 255 depending on the platform in the returned array - these characters are discarded by the terminal. Note that if the terminal is not a real terminal which is usually the case what it receives may already have been processed by something else first. For instance the X- Window system defines its own character mapping the xrdb utility can do this which takes effect before our terminal even sees the character. Likewise PC keyboards actually generate 16 bit values which are translated by the operating system into characters before we see them. On UNIX platforms only we can also alter which control characters trigger which operations using SetControlChars. This takes a list of key-value pairs as arguments and applies them to the terminal s built-in list. Each pair consists of a name as returned by GetControlChars followed by the character or character value. A value of zero disables the operation. For example we can redefine or disable the delete key by setting the ERASE operation SetControlChars ERASE 0 disables delete SetControlChars ERASE 2 sets delete to control-B In the following program we extract and print the list of control characters alter some of them and then print it out again. Note that the attempted alterations will not produce any effect on Windows systems and will in fact generate an error usr bin perl .