how to detect F1-F12 within python curses

Question

k = stdscr.getch()
if k == curses.KEY_UP:
    sys.stdout.write('KEY_UP')
elif k == curses.KEY_F1:
    sys.stdout.write('KEY_F1')
elif k == 113:
    break
else:
    pass

https://docs.python.org/2/library/curses.html

The above code can be used to detect 'q' and arrow_up. However, it cannot be used to detect F1.

Question> Is there a way in python curses that I can use to detect the special function keys?

[Update]

My terminal type is xterm.

elif k == 269: # 'F5'
elif k == 270: # 'F6'
elif k == 271: # 'F7'
elif k == 272: # 'F8'
elif k == 273: # 'F9'
elif k == 27: # 'ESC'
    special_keys = [stdscr.getch(), stdscr.getch(), stdscr.getch(), stdscr.getch()]
    if special_keys == [91, 49, 49, 126]:
        sys.stdout.write('F1\n')
    if special_keys == [91, 49, 50, 126]:
        sys.stdout.write('F2\n')
    if special_keys == [91, 49, 51, 126]:
        sys.stdout.write('F3\n')
    if special_keys == [91, 49, 52, 126]:
        sys.stdout.write('F4\n')

Based on the suggestions from @pbuck, I tested my terminal and listed the results above. I am not sure whether this solution is portable or not. Since @pbuck only suggested that I should use the next two keys after ESC. For my case, I have to extract the next four keys.

If you're not able to detect F1, etc., it's because you have `TERM` set incorrectly. — Thomas Dickey, Jun 02 '17 at 21:24
@ThomasDickey, so what is the correct TERM I should use. If I knew the right TERM, I would not post the question here. — q0987, Jun 06 '17 at 12:37
Different terminals need different values of **`TERM`** (your question does not state which terminal you are using). — Thomas Dickey, Jun 12 '17 at 23:19

pbuck · Answer 1 · 2017-06-02T17:28:26.060

Function keys are mapped by your terminal. For example, when you press the F1 key, your terminal (may) be actually sending a sequence like Esc-OP (or ^[OP if you prefer). So, on stdscr.getch(), if it is Esc, grab the next few characters to determine with FKEY.

Hard coding the particular escape sequence isn't great, but function key sequences are dependent upon the interface (i.e., your xterm, console, terminal window, etc). For *nix, that usually means terminfo database. On some interfaces (like my emacs shell), nothing is sent because the terminal driver intercepts it!

You can determine what is being sent for a particular interface using tput and cat -A, because:

$ tput kp1 | cat -A
^[OP
$ tput kp10 | cat -A
^[[21~

However, in my case with same computer, using console window yields:

$ tput kp1 | cat -A
^[[21~
$ tput kp10 | cat -A
^[[[A

@q0987 update my post with more examples, hope it's helpful. — pbuck, Jun 02 '17 at 17:29
would welcome input as to why this answer was down voted -- perhaps I could make it better. — pbuck, Jun 03 '17 at 05:42

user11743971 · Answer 2 · 2019-07-05T13:24:20.797

Does this way satisfy your need?

nKey = stdscr.getch()
sKeys = "%d" % nKey
if nKey == 27 :
    stdscr.nodelay(True)
    for n in range(0,10):
        nKey = stdscr.getch()
        if nKey == curses.ERR :
            break
        sKeys += " %d" % nKey
    stdscr.nodelay(False)
print ( "Key : %s" % sKeys )

It will show like as below:

[F1]    "27 91 49 49 126"
[F2]    "27 91 49 50 126"
[HOME]  "27 91 49 126"
[END]   "27 91 52 126"

This is an easy way to see the result visibly but using list variable may be easy for if statements later. It delays for [ESC] key. I found this post for changing its behaviour.

--Append-- We can avoid [ESC]'s delay with this, but it affects many key-codes and mouse input.

stdscr.keypad(False)

how to detect F1-F12 within python curses

2 Answers2