The TTY demystified

marcell mars's personal annotations on this page

Marcell bookmarked on 2009-06-15 linux text ui display

"The TTY subsystem is central to the design of Linux, and UNIX in general. Unfortunately, its importance is often overlooked, and it is difficult to find good introductory articles about it. I believe that a basic understanding of TTYs in Linux is essential for the developer and the advanced user."

The TTY subsystem is central to the design of Linux, and UNIX in general.
Unfortunately, its importance is often overlooked, and it is difficult to find
good introductory articles about it. I believe that a basic understanding of
TTYs in Linux is essential for the developer and the advanced user.

This link has been bookmarked by 15 people . It was first bookmarked on 15 Jun 2009, by Javier Neira.

22 Nov 09

Russ
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W. Sarka
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Sébastien Bocq
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Sergey Kucherenko
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jeunium jeunium
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17 Jun 09

Yuri Baranov
linux kernel TTY HOWTO_FAQ
16 Jun 09

Thomas Buscher
knowuh not saying
Fun guide to tty configuration, with great pictures and a lovely nostalgic tone.

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gabriele Domenichini
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martin t
linux tty
Yun Huang Yong
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Rajkumar Singh
The TTY demystified

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15 Jun 09

Régis Gaidot
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marcell mars
"The TTY subsystem is central to the design of Linux, and UNIX in general. Unfortunately, its importance is often overlooked, and it is difficult to find good introductory articles about it. I believe that a basic understanding of TTYs in Linux is essential for the developer and the advanced user."

linux text ui display
- The TTY subsystem is central to the design of Linux, and UNIX in general.
  Unfortunately, its importance is often overlooked, and it is difficult to find
  good introductory articles about it. I believe that a basic understanding of
  TTYs in Linux is essential for the developer and the advanced user.
Javier Neira
linux unix sysadmin tty intro
- UART (Universal Asynchronous Receiver and
  Transmitter)
- So as a convenience, the operating system
  provides an editing buffer and some rudimentary editing commands (backspace,
  erase word, clear line, reprint), which are enabled by default inside the
  line discipline
- 8 more annotations...
- - Most interactive applications
    (editors, mail user agents, shells, all programs relying on curses or
    readline) run in raw mode, and handle all the line editing commands
    themselves.
  - a particular triplet of UART driver, line discipline instance and
    TTY driver may be referred to as a TTY device, or sometimes just TTY.
  - but there is no UART or physical terminal involved anymore
  - Things get more flexible (and
    abstract) if we move the terminal emulation into userland. This is how
    xterm(1) and its clones work:
  - If you look inside the
    kernel source code, you will find that any kernel code which is waiting for an
    event must check if a signal is pending after schedule() returns, and abort the
    syscall in that case.
  - Job control is what happens when you press ^Z to suspend a program,
    or when you start a program in the background using &
  - UNIX files, including the TTY device file, can of course be read from and
    written to, and further manipulated by means of the magic ioctl(2) call (the Swiss
    army-knife of UNIX) for which lots of TTY related operations have been defined.
    Still, ioctl requests have to be initiated from processes, so they can't be
    used when the kernel needs to communicate asynchronously with an
    application.
  - So a signal is a crude mechanism that allows the kernel to communicate
    asynchronously with a process. Signals in UNIX aren't clean or general; rather,
    each signal is unique, and must be studied individually.