How to use ESC sequences to make terminal region scrollable

ansi-termescape-charactersterminal

I have a stm32f1 controlled device that uses USART/USB port to implement a user control interface. Using a standard terminal software (putty/minicom) a user has an ability to enter simple command in device shell.

There is a problem. In case of many incoming info packets, they print over shell prompt making entering new commands hard.

I plan to split a terminal screen on two areas: a one line prompt and a scrollable area for incoming packets.

I have tried to use the following escape sequence:

162 72 r * DECSTBM - Set top and bottom margins (scroll region on VT100)
        [4;20r = Set top margin at line 4 and bottom at line 20

but still can not find a good tutorial which is described a right way that will help me to solve my problem.

Best Answer

Reading source code is helpful, but the suggested examples are complicated. Most useful programs like the one OP is asking about use escape sequences via termcap or curses interfaces. Doing it with curses would be much simpler. Here are the steps needed with termcap:

get the terminal description (including the cursor-movement, scrolling region, erase-line, index)
initialize the terminal to "cbreak" (semi-raw) mode to allow keeping the prompt on a single line.
move the cursor to the line where the prompt should be
erase the line
write the prompt
get the input command

Meanwhile (the reference to packets makes it appear that OP wants to display them concurrently with reading input)

move the cursor to the bottom line of the scrolling region
set the scrolling region
write a line of the package (ending with newline, or using the index escape sequence)
reset the scrolling region to its default (full-screen)
move the cursor back to the command-line, continue reading commands

Best practice does not attempt to use cursor-addressing outside the scrolling region, so there will be a lot of setting/resetting of the scrolling region, each time the program switches between the two sections of the screen.

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Is there a pastebin service that supports terminal escape sequences

Termbin.com supports what you need.

$ grep --color=force foo /etc/motd | nc termbin.com 9999
http://termbin.com/xxxx

$ curl http://termbin.com/xxxx

You'll get exactly what you sent.

The service is running on a free and open software called Fiche so you can also install your own.

Scripting – Use Less Without ESC Escape Characters

Use -R flag:

-r or --raw-control-chars

Causes "raw" control characters to be displayed. The default is to display control characters using the caret notation; for example, a control-A (octal 001) is displayed as "^A". Warning: when the -r option is used, less cannot keep track of the actual appearance of the screen (since this depends on how the screen responds to each type of control character). Thus, various display problems may result, such as long lines being split in the wrong place.

-R or --RAW-CONTROL-CHARS

Like -r, but only ANSI "color" escape sequences are output in "raw" form. Unlike -r, the screen appearance is maintained correctly in most cases. ANSI "color" escape sequences are sequences of the form:
           ESC [ ... m
where the "..." is zero or more color specification characters For the purpose of keeping track of screen appearance, ANSI color escape sequences are assumed to not move the cursor. You can make less think that characters other than "m" can end ANSI color escape sequences by setting the environment variable LESSANSIENDCHARS to the list of characters which can end a color escape sequence. And you can make less think that characters other than the standard ones may appear between the ESC and the m by setting the environment variable LESSANSIMIDCHARS to the list of characters which can appear.

From less man page.

Best Answer

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Is there a pastebin service that supports terminal escape sequences

Scripting – Use Less Without ESC Escape Characters

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