Control cursor position also at bottom of window Post: 303043675

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Top Forums Shell Programming and Scripting Control cursor position also at bottom of window Post 303043675 by Ralph on Monday 3rd of February 2020 03:36:05 PM

02-03-2020

Registered User

Control cursor position also at bottom of window

I have a slight problem controlling the cursor position in a Bash terminal window. I have a function ask a question and then wait for an answer which is either 'y' or 'n' or a carriage return. Whenever the user enters anything else it just erases the answer and waits for the next one. However, the script behaves differently when the cursor is on the bottom line of a window as compared to any other line.

Code:

#!/bin/bash

# -----
# function: askYesOrNo
# purpose : ask question passed as $1
# return  : 0 if answer was y or Y, 
#           1 otherwise
# -----
function askYesOrNo {
        printf "\e[1;31;47m$1 [Y|n]\e[0m "      # print $1 in color
        printf "\e[s"                           # save cursor x-pos

        while true ; do
                read answer
                if [ -z "$answer" ] ; then
                        return 0
                elif [ "$(tr -d "NnYy" <<< $answer)" != "$answer" ] ; then
                        break
                fi
                # restore cursor x-pos, erase rest of line
#               printf "\e[u\e[K"     
                # restore cursor x-pos, erase rest of line
                printf "\e[u\e[1A\e[K"      
        done
        if [ "${answer^}" == "Y" ]; then
                return 0
        fi
        return 1
}


for (( i = 100, max = 110; i <= max; i++ )) ; do
        printf " %d\n" $i
        if [ $i -eq $max ] ; then
                if askYesOrNo "Do you wish to continue?" ; then
                        (( max += 10 ))
                fi
        fi
done

The for-loop is the 'productive' part. It just puts out numbers in a column. Every 10 numbers it asks if the user wants to continue and uses the function askYesOrNo for that purpose.

The problem lies with the two lines in the function askYesOrNo (at the end of the while-loop) and when the user enters an answer that is not Y, y, N, n or Enter. The first line (now commented out) works fine when the cursor is not in the bottom line of the window. But if it is then the window scrolls up and the next answer appears in the next line.

The second version moves the cursor one line up and that's fine with the cursor at the bottom of the window but not if the question is asked elsewhere.

How can I get this to work in every situation?

Ralph

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LEARN ABOUT DEBIAN

purity-ng

PURITY-NG(6)							   Games Manual 						      PURITY-NG(6)

NAME

       purity-ng - general purpose purity testing software

SYNOPSIS

       purity-ng [OPTION]...  list|FILE|TESTNAME

DESCRIPTION

       Purity  is  an  interactive purity test program with a simple, user interface and datafile format.  For each test, questions are printed to
       the your terminal, and you are prompted for an answer to the current question.  At a prompt, these are your choices:

	      y      Answer "yes" to the question.
	      n      Answer "no" to the question.
	      b      Backup  one  question, if you answered it incorrectly, or someone is watching you take the test, and you don't (or do) want to admit a different answer.
	      s      Print your current score on the test you are taking.
	      q      Quit the test, and print the current score.
	      ?      Print a help screen for the current prompt.

       At the end of the test, your score is printed out.  For most purity tests, lower scores denote more "experience" of the test material.

OPTIONS

       --version
	      print current version of purity-ng

       -h, --help
	      show the help message and exit

       -p     print the test without prompting for answers.

       -r     decrypt the test using the Rot 13 algorithm.

       To get a list of all purity tests available globally on your system, run purity-ng list.

AUTHORS

       purity was originally written by Eric Lechner in 1989.  purity-ng is a reimplementation of purity in Python for modern systems, written	by
       Simon Fondrie-Teitler and Luke Faraone.

       This manual page was written by Luke Faraone.

BUGS

       If you find bugs in the application, please report these to <https://bugs.launchpad.net/purity-ng> or to your distribution's distributor.

SEE ALSO

       purity(6)

       Running purity-ng format provides documentation about the datafile format.

       Additional documentation is available online at <http://packages.python.org/purity-ng>.

								  January 7, 2011						      PURITY-NG(6)

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