Is there go up line character? (Opposite of n)

Question

I would like to overwrite something on a line above in a serial console. Is there a character that allows me to move up?

Asked By: Sponge Bob

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Source

Answer 1

No, not really easily, for that you’d have to use something like the curses library, especially if you want to have more control over cursor placement and do more things programatically.

Here’s a link for the Python docs on Programming with Curses, and this short tutorial/example might be of interest too.

I just found this note in the docs in case you are using Windows:

No one has made a Windows port of the curses module. On a Windows
platform, try the Console module written by Fredrik Lundh. The Console
module provides cursor-addressable text output, plus full support for
mouse and keyboard input, and is available from
http://effbot.org/zone/console-index.htm.

I believe for C++ there is the NCurses library, the linked page has a section on moving the cursor if you want to poke around with C++. Also there’s the NCurses Programming HowTo.

Long time ago I used the curses library with C quite successfully.

Update:

I missed the part about running this on a terminal/serially, for that the ANSI escape sequence, especially for a simple task like yours, will be easiest and I agree with @SvenMarnach solution for this.

Answered By: Levon

Answer 2

Most terminals understand ANSI escape codes. The relevant codes for this use case:

"33[F" – move cursor to the beginning of the previous line
"33[A" – move cursor up one line

Example (Python):

print("33[FMy text overwriting the previous line.")

Answered By: Sven Marnach

Answer 3

I may be wrong but :

#include <windows.h>


void gotoxy ( int column, int line )
{
  COORD coord;
  coord.X = column;
  coord.Y = line;
  SetConsoleCursorPosition(
    GetStdHandle( STD_OUTPUT_HANDLE ),
    coord
    );
}

in windows standard console.

Answered By: user2244507

Answer 4

for i in range(10):  
    print("Loading" + "." * i) 

    doSomeTimeConsumingProcessing()

    sys.stdout.write("33[F") # Cursor up one lin

Try this in Python and replace doSomeTimeConsumingProcessing() with any routine needed, and hope it helps

Answered By: user7380054

Answer 5

Carriage return can be used to go to the beginning of line, and ANSI code ESC A ("33[A") can bring you up a line. This works on Linux. It can work on Windows by using the colorama package to enable ANSI codes:

import time
import sys
import colorama

colorama.init()

print("Line 1")
time.sleep(1)
print("Line 2")
time.sleep(1)
print("Line 3 (no eol)", end="")
sys.stdout.flush()
time.sleep(1)
print("rLine 3 the sequel")
time.sleep(1)
print("33[ALine 3 the second sequel")
time.sleep(1)
print("33[A33[A33[ALine 1 the sequel")
time.sleep(1)
print()  # skip two lines so that lines 2 and 3 don't get overwritten by the next console prompt
print()

Output:

> python3 multiline.py
Line 1 the sequel
Line 2
Line 3 the second sequel
>

Under the hood, colorama presumably enables Console Virtual Terminal Sequences
using SetConsoleMode.

Answered By: jtpereyda

Answer 6

A simple way based on @Sven Marnach answer:

print(f'33[Arxxx')

33[A: Move cursor one line up.
r: Move the cursor to the beginning of the line.
xxx: The string to be printed. {xxx} if it is a variable

If you have some extra characters from the previous line after your string, overwrite them with white space, depending on the length of the previous line. Below I added 10 white spaces.

print(f'33[Arxxx{' '* 10}')

Answered By: N. Osil

Is there go up line character? (Opposite of n)

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