![]() This dies if N is not a positive number between 0 and 255 (inclusive). Make the foreground the color N in the xterm 256 color chart. Use the background color for the text color, and the text color for the background. Put the cursor back to where you saved it. Make the text dark (however your terminal does that). Move the cursor up N lines, to the start of the line Move the cursor down N lines, to the start of the line Make the text invisible (if your terminal handles that). Each of these start at the current cursor position. Make the text blink (however your terminal does that).Ĭlear the part of the screen as indicated. ![]() Make the background the named color and bright (however your terminal does that). For example, ignore the ANSI sequences in computing length. Routines for dealing with text that contains ANSI code. I want to emit the sequence in a stream without knowing what's coming up. There are several modules that come close to this, but so far everything is incomplete or requires you to know all of the upcoming text ahead of time so you can use of it as an argument to a function. You can emit these without knowing what's coming up. Subroutines to deal with ANSI terminal sequences. ![]() Print bold, underline, text_red, "Hello", reset DESCRIPTION For instance, the TECO editor would display a dollar sign to the user each time the ESC was pressed, as it used this for a command separator the same way one might use a semicolon in coding today.Antsy - Streaming ANSI escape sequences SYNOPSIS use Antsy qw(:all) The third solution to the problem was to simply have the host ignore special function keys altogether and take the incoming byte stream as literal. e.g., use ESC Space to force the escape through, the ESC cancels one prompt, but the space unintendedly acknowledges the next. The problem is sometimes those characters caused side effects to an application, nasty ones, and interesting cases could arrive where trying to naively fake out the system could get you into trouble. Of course, an 'invalid' ESC sequence meant the ESC was literal, but this required seeing what the following bytes were before you could act on them (hence the timeout solution). Only years later did we start emulating terminals and thus rose the need to emulate their escape sequences rather than taking the behaviors out of the content stream. Remember, in the days of serial ports, which was when these terminals were in use, when a character was pressed, it was sent immediately. It exactly the same thing we do when quoting backslash characters in strings, a "\" really means a "\" because we have to satisfy the compiler's lexical phase. As no escape sequence ever consisted of a double escape character, it signaled a special condition. Two, require the user to press ESC twice for every literal ESC desired. And, working under the assumption that a terminal would send a block of characters in its buffer immediately, it would internally time out and take ESC to mean just ESC. The host would have the responsibility of watching not just what came in, but when. One, send the ESC and then delay for some amount. This then left the very real problem of how to send a literal orphaned ESC. When you pressed a function key, the terminal would send an ESC character followed by some pre-canned sequence for a function key, arrow, or action. In theory the server should never throw you a meaningless orphaned ESC character as the terminal would sit there and wait for a sequence. ESC [ 12 34 H would go to row 12, column 34. Even ESC [ row col H would take a numerical row/col, e.g. Switch the J to a K, and now it would clear the line, rather than the screen, the same way. The '2' in the ESC [ 2 J meant both from the cursor to the top (zero), and from the cursor to the end (one). What was really going on was that the open square bracket (there was no close bracket) said that a list of arguments, usually numeric, was coming. The VT-100 series used ESC [ H for home, and ESC [ 2 J for clear to end of screen. ESC # 6 to double-width characters.įor instance on a H-19 / VT-52 terminal, ESC H meant home, ESC E meant clear screen and home, ESC J meant clear to end of screen, etc. In general the rule was to swallow the incoming characters until an alphabetic or symbolic character was seen, inclusively, although some special cases such as symbols which might grab one additional character, e.g. This usually put the terminal into a simple state machine. The escape character, ASCII 27, was used to indicate that the following sequences of characters had special meaning. There is no such thing as an "escape sequence" for the ESC key on a VT-100 (or other terminals that used escape sequences).
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