Terminals

All of the above is a preamble to saying that the need to program terminal devices is less frequent than it used to be.

62.1 Overview

Both a conventional terminal and a terminal emulator have an associated terminal driver that handles input and output on the device. (In the case of a terminal emulator, the device is a pseudoterminal.)

driver 的作用 handle input and output

When performing input, the driver is capable of operating in either of the following modes:

  1. Canonical mode
  2. Noncanonical mode

    如何设置这两种模式 ?

The terminal driver also interprets a range of special characters, such as the interrupt character (normally Control-C) and the end-of-file character (normally Control-D).

原来是 driver 的工作，我想找到对应的代码的位置

A terminal driver operates two queues (Figure 62-1): one for input characters transmitted from the terminal device to the reading process(es) and the other for output characters transmitted from processes to the terminal

terminal device —> the process —> terminal 图 62-1 不错的

62.2 Retrieving and Modifying Terminal Attributes

The tcgetattr() and tcsetattr() functions retrieve and modify the attributes of a terminal

Setting the line discipline can be relevant when programming serial lines.g

62.3 The stty Command

讲解使用 stty 命令　可以替代 tcgetattr 和 tcsetattr　的作用 some part is skiped

62.4 Terminal Special Characters

一个列表 举的例子还是很有意思

62.5 Terminal Flags

The following paragraphs provide more details about some of the termios flags.

继续描述 termios 的几个 flags ，flags 中间包含的很多变量已经没有作用了

62.6 Terminal I/O Modes

  1. describe these two modes in detail.
  2. describe three useful terminal modes—cooked, cbreak, and raw
  3. show how these modes are emulated on modern UNIX systems by setting appropriate values in the termios structure.

62.6.1 Canonical Mode

62.6.2 Noncanonical Mode

无论是 MIN 还是 TIME 的作用是限制 read 函数何时返回，本文介绍了四种取值的含义和适用的场景

62.6.3 Cooked, Cbreak, and Raw Modes

通过配置 termios 参数形成三种常用的模式 例子似乎非常的有意思

62.7 Terminal Line Speed (Bit Rate)

The cfgetispeed() and cfsetispeed() functions retrieve and modify the input line speed. The cfgetospeed() and cfsetospeed() functions retrieve and modify the output line speed.

62.8 Terminal Line Control

The tcsendbreak(), tcdrain(), tcflush(), and tcflow() functions perform tasks that are usually collectively grouped under the term line control. (These functions are POSIX inventions designed to replace various ioctl() operations.)

对于 driver 两个 queue 的控制

62.9 Terminal Window Size

运行于终端中间的程序可以通过 ioctl 捕获 signal 获取当前的中断的大小

skip the example

62.10 Terminal Identification

The isatty() function enables us to determine whether a file descriptor, fd, is associated with a terminal (as opposed to some other file type).

The isatty() function is useful in editors and other screen-handling programs that need to determine whether their standard input and output are directed to a terminal.

62.11 Summary

to read ! 总体来说，都是操纵 termios 的内容而已，并且逐个讲解其中的作用是什么。

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