Question

How can I find out how may character are there in a line before the end line in an interactive shell using python? (Usually 80)

Answer 1

You can use the tput utility to query the number of lines and columns available in the terminal. You can execute it using subprocess.Popen:

>>> import subprocess
>>> tput = subprocess.Popen(['tput', 'cols'], stdout=subprocess.PIPE)
>>> int(tput.communicate()[0].strip())
180

The same principle can also be applied to query the $COLUMNS variable as mentioned by gregseth:

>>> tput = subprocess.Popen(['echo $COLUMNS'], shell=True, stdout=subprocess.PIPE)
>>> int(tput.communicate()[0].strip())
180

Lastly, if you are OK with using the curses library for such a simple problem, as proposed by Ignacio Vazquez-Abrams, then note that you’ll need to perform three statements, not one:

>>> import curses
>>> curses.setupterm()
>>> curses.tigetnum('cols')
180

If the terminal is resized, then setupterm will need to be called before the new terminal width can be queried using tigetnum.