CODEWITHSUNDEEP
bashshellsed
Marko
Marko

Reputation: 83

Read and echo on some line Bash

Hello I want to read a command and print it on some line.

Example: I use a function where I read values into a and b then echo these values and the result of some operation:

1. $ 5 plus 5
2. $  = 10

On 1. line I am reading to variables a and b, after that I hit enter and echo the result but on a new line. Read command need enter and enter in terminal give you new line.

How it should look like:

1. $ 5 plus 5 = 10

I tried to use sed with no luck.

EDIT: I am using simple:

$read a b c
#a=5 b=plus c=5

Upvotes: 0

Views: 436

Answers (1)

glenn jackman
glenn jackman

Reputation: 246877

Using ANSI escape codes to go up one line and clear the line:

#!/bin/bash
read -p 'equation: ' operand1 operation operand2
# magic to transform "plus" to "+" left to the reader
let answer="$operand1 $operation $operand2"
echo -e "\033[F\033[K$operand1 $operation $operand2 = $answer"

ref: https://en.wikipedia.org/wiki/ANSI_escape_code

Upon reflection, I'd break that into 2 statements for some clarity:

echo -ne "\033[F\033[K"   # move the cursor and clear the line
echo "$operand1 $operation $operand2 = $answer"

Upvotes: 1

Related Questions