Read a multiline text from a console - supporting arrow keys

Shell Programming and Scripting
1

Hi,

I try to read a multiline text from a console and write it to a file using a bash script. I want to end reading from a console if a user types the [Enter] key twice. I tried this loop:

while read LINE; do
if [ ! $LINE ] 2>/dev/null; then
   break
fi
echo -e ${LINE} >> $file
done

However, it doesn't support the arrow keys

Do you have any idea?

Thanks in advance

2

Hi,

Try this one,

readmultiline.sh

#! /usr/bin/env bash
file=file1
while read LINE; do
if [ -z "$LINE" ]; then
   break
fi
echo -e "${LINE}" >>$file
done

$ bash readmultiline.sh
Unix is god^[[B^[[A^[[C^[[D
Linux^[[A^[[D^[[B^[[C^[[A

$ cat -A file1
Unix is god^[[B^[[A^[[C^[[D$
Linux^[[A^[[D^[[B^[[C^[[A$

Cheers,
Ranga :slight_smile:

1 Like
3

What do you mean? Do you want to skip through earlier input lines with the arrow keys?

1 Like
4

try this..

while [[ $a < 2 ]]
do
read line
if [[ "$line" != "" ]]
then
let a=0
echo $line >> file_temp
else
let a++;
fi
done

It will stop if user press two consecutive enters..(Means two consecutive Blank inputs..):slight_smile:

1 Like
5

Hi,

Thank you for your replies. However, I didn't express myself clearly, I just want to be able to move a cursor using the arrow keys while reading an input from a console, because now after pressing an arrow key I got e.g. ^[[D^[[C^[[A^[[B output instead of moving my cursor

6

Again, what's your purpose? Do you want to skip back in your input lines or do you just want to move left and right? The latter can be achieved - in bash, may be unavailable in other shells - by switching on the readline library functions using the -e option: read -e line The former is much harder to do, like using numbered variables or an array, and writing to the output file consistently will become a nightmare; you might be better off using an editor.

1 Like
7

I just want to move left/right and if it's possible also up and down, but honestly I don't have any idea how to achieve the latter. Anyway, thank you for your solution with the -e option

8

What's your system? What's your shell? In BASH, you can use read -e to read lines using readline mode, which lets you edit with left-right keys, but that still doesn't support multiple lines. If you really need deluxe input maybe you should just fire up a text editor for them. nano for instance can be used in restricted mode to prevent them from changing to different files, etc.

1 Like
9

I'm using the Bash shell, I work on the SunOS 5.9 OS. I'm just wondering if there is a simple way to create a script which would support an input which contains multiple lines, however, it seems that there isn't

Thanks for your reply