Arrow keys not working while entering data for input() function

Question

In linux, the arrow keys don't work when I try to enter data for an input() function. I get escape characters. See below (when I pressed left arrow key).

dp@hp:~$ python3 -c "x = input('enter a number '); print(x)"
enter a number 123^[[D^[[D

I have readline installed (I am able to import it in the python shell). The arrow keys work fine in the interactive interpreter but not in the above case (or when I execute input() from a script).

What could be the reason?

Answer 1

The documentation says:

If the readline module was loaded, then input() will use it to provide elaborate line editing and history features.

In your example, you haven't loaded the readline module. Compare the behavior of this:

x = input('enter a number:')
print(x)

To this:

import readline
x = input('enter a number:')
print(x)

The second example will behave as you expect (readline support is active, arrow keys work, etc) while the first example will not have readline support.

On the command line, this would be:

python3 -c "import readline; x=input('enter a number '); print(x)"