GeezerVison is showing github.com — `getpass`'s `echo_char` should not affect keyboard shortcuts · Issue #138577 · python/cpython
getpass's echo_char should not affect keyboard shortcuts #138577
DescriptionBug report
Bug description:
Hitting Ctrl+U should clear the line but this is badly handled when echo_char is given:
>>> getpass.getpass()
Password:
'bar'
>>> getpass.getpass(echo_char="*")
Password: *******
'foo\x15bar' See #138514 (comment).
This issue stems from the fact that we switch to non-canonical mode (https://www.man7.org/linux/man-pages/man3/termios.3.html). The rationale is that in canonical mode, we only have a line-by-line feedback (so we would see the characters only when we hit ENTER, which is not really useful...)
CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux
Linked PRs
Activityyagggi commented on Sep 8, 2025 Hi @picnixz , this seems to be a trival fix, would you mind if I give it a try? picnixz commented on Sep 8, 2025 I'm not sure this is a trivial fix actually as it's about dealing with readline capabilities. It's not just Ctrl+U that is badly handled, it's all keyboard shortcuts so this may be really tricky. yagggi commented on Sep 8, 2025 Oh I see, yeah then it's tricky. Since ICANON is disabled, the best I can think of is simulating erasing logic from tty, but I'm not sure if it's worthy or not.
I'm not going to try to fix this, hope there will be a better solution. picnixz commented on Sep 8, 2025 Since 3.14 is almost released, I think we should just mention this. I don't have enough time to investigate this and I don't know if we can fix it robustly.
We support erasing a single character but we do not support erasing everything that was written via Ctrl+U. If you want, you can write a documentation for that though.
@yagggi yagggi commented on Sep 8, 2025 picnixz commented on Sep 8, 2025 I'm actually wondering whether it was the correct way to do it. Shipping a feature that is not entirely complete makes me feel bad and this limitation may be annoying. Maybe we should instead put this feature in 3.15.
@donbarbos How does it work on a Windows machine? do you have access to one? for instance what if I hit Ctrl+Backspace? does it work correctly? if not, we should perhaps revisit the entire feature and use a REPL-like approach if possible. Ok on Windows for 3.13.2, the normal behavior doesn't support those keyboard shortcuts (I hit Ctrl+Backspace) so maybe it's fine to have inconsistencies "everywhere"...
>>> getpass.getpass()
Password:
'abc\x7fdef' Summary:
- On Unix, keyboard shortcuts work with the default behavior (old). On Windows, those shortcuts don't work.
- On Unix, keyboard shortcuts no longer work with
echo_char. On Windows, I think they will still fail.
- Should we ship 3.14 with something that has a weird behavior on Unix? for now, I asked for documentation but maybe it's just better to avoid it entirely on Unix until we can make it work consistently (whether we use
echo_char or not).
cc @hugovk picnixz commented on Sep 8, 2025 I'm adding the release-blocker label to draw attention. yagggi commented on Sep 8, 2025 I have similar worries, especially in my opinion, echoing astars when typing password is a rarely seen behavior on Unix command-line interfaces, it's quite normal on GUI applications though. Not sure if it's a good idea to have echo_char in standard library. picnixz commented on Mar 30, 2026 We decided not to backport the fix as a state machine was necessary to handle this (i.e. we needed a simple line editor for this to work). Note that this fix only affects people using the *echo_char* parameter. Default mode is unaffected (as it relies on readline) and will still not work properly.
More precisely: to be able to use keyboard shortcuts you need to be in a feedback mode. If you have a hidden password, being able to use keyboard shortcuts won't help as you do not necessarily know where you are... so it's better to just support erasing the last character (which is already the case).
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