Maybe I wrote smth strange in a question title, I'l try to explain.
I'm trying to do password input as in linux-based systems (no symbols shows while you type).
I found one function that did it.
def getchar():
import tty, termios, sys
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
try:
tty.setraw(sys.stdin.fileno())
ch = sys.stdin.read(1)
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
return ch
pwd = ''
print('Type password:', end=' ') # HERE IS THE PROBLEM
while True:
ch = getchar()
if ch == '\r':
break
pwd += ch
print(pwd)
If I do not use end argument it looks like that:
But with end argument:
Line 'Type password:' will appear after while loop end.
Why is this and what can I do?
By default, sys.stdout is line buffered, which means that anything written to it is buffered up until a newline is seen.
Because you replaced the standard end='\n' with a space, no newline is seen yet and the buffer is not flushed. Set flush=True to force a buffer flush anyway:
print('Type password:', end=' ', flush=True)
Related
What I am trying to do is make a simple pi memorization game in Python. What I need is a way to get input from the user without having to press 'enter' after every character. It sounds like I need something like getch, but I can't get it to work. I got a getch-like function from here: https://gist.github.com/chao787/2652257#file-getch-py. I don't really understand anything that's in there. When I do 'x = getch.getch()' it says "AttributeError: '_Getch' object has no attribute 'getch'". It looks like msvcrt can do it for Windows, but I have a Mac. It also looks like curses is a thing that has getch, but it says I need to do initscr first, but then I get the error "File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/curses/__init__.py", line 30, in initscr
fd=_sys.__stdout__.fileno())
_curses.error: setupterm: could not find terminal".
This is my file just using input, where you would have to press enter every time (I actually put in 1000 digits, not an ellipsis).
pi = '3.1415926535...'
def main():
print('Welcome to PiGame!')
pigame()
while True:
yn = input('Play again? y/n ')
if yn == 'y':
pigame()
else: return
def pigame():
n=0
print('Go!')
while n<=1000:
x = input()
if x == pi[n]:
n += 1
else:
print('I\'m sorry. The next digit was '+pi[n]+'.')
print('You got to '+str(n)+' digits!')
return
print('You got to 1000! Hooray!')
You can define your own version of getch using the termios, sys and tty packages:
def getch():
import termios
import sys, tty
def _getch():
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
try:
tty.setraw(fd)
ch = sys.stdin.read(1)
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
return ch
return _getch()
This is a tested (on RPi, Py 3) code that can read a specified length of chars without need to hit Enter button
But consider one thing :
This must run on terminal otherwise raises an error
import termios, sys , tty
def _getch():
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
try:
tty.setraw(fd)
ch = sys.stdin.read(1) #This number represents the length
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
return ch
getch = _getch()
print(getch)
I am wondering how to get Python to validate an input line and complete tasks using the input as it's being typed.
For example:
alphabet = "abcdefghijklmnopqrstuvwxyz"
useralphabet = input("Please enter however much of the alphabet you know:")
while(useralphabet in alphabet):
break
print("You know", 26 - len(useralphabet), "letters of the alphabet!")
Obviously I know this code won't work as intended, but I hope it demonstrates the idea of what I'm trying to do, i.e., get the user to input text until that they have entered is no longer part of the specified string.
The answer depends on your OS (operating system). Usually the OS hands over the input string to python only after you hit the ENTER key. If you need to do it as you type, you may need to invoke some system dependent calls to turn off input buffering.
See Python read a single character from the user for more on this
Here is a working example (Tested with Python 3.8.6 on Linux). See this answer if you need to modify for other systems.
The hinput function reads chars as they are typed and calls on_char for each new character passing both the new char and the entire line.
In my example when the user types x the on_char function returns True which causes the hinput function to stop waiting for new input.
If the user types hello it is autocompleted to hello, world and also terminates hinput
import sys
import termios
import tty
from typing import Callable
def main():
hinput("prompt: ", on_char)
return 0
def on_char(ch: str, line: str) -> bool:
if ch == 'x':
sys.stdout.write('\n')
sys.stdout.flush()
return True
if line+ch == 'hello':
sys.stdout.write("%s, world\n" % ch)
sys.stdout.flush()
return True
return False
def hinput(prompt: str=None, hook: Callable[[str,str], bool]=None) -> str:
"""input with a hook for char-by-char processing."""
fd = sys.stdin.fileno()
old = termios.tcgetattr(fd)
inpt = ""
while True:
sys.stdout.write('\r')
if prompt is not None:
sys.stdout.write(prompt)
sys.stdout.write(inpt)
sys.stdout.flush()
ch = None
try:
tty.setraw(sys.stdin.fileno())
ch = sys.stdin.read(1)
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old)
if hook is not None and hook(ch, inpt):
break
if ord(ch) == 0x7f: #BACKSPACE
if len(inpt) > 0:
sys.stdout.write('\b \b')
inpt = inpt[:-1]
continue
if ord(ch) == 0x0d: #ENTER
sys.stdout.write('\n')
sys.stdout.flush()
break
if ch.isprintable():
inpt += ch
return inpt
if __name__ == '__main__':
sys.exit(main())
I have this script
import sys, os, termios, tty
home = os.path.expanduser("~")
history = []
if os.path.exists(home+"/.incro_repl_history"):
readhist = open(home+"/.incro_repl_history", "r+").readlines()
findex = 0
for j in readhist:
if j[-1] == "\n":
readhist[findex] = j[:-1]
else:
readhist[findex] = j
findex += 1
history = readhist
del readhist, findex
class _Getch:
def __call__(self):
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
try:
tty.setraw(sys.stdin.fileno())
ch = sys.stdin.read(3)
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
return ch
while True:
try:
cur = raw_input("> ")
key = _Getch()
print key
if key == "\x1b[A":
print "\b" * 1000
print history[0]
history.append(cur)
except EOFError:
sys.stdout.write("^D\n")
history.append("^D")
except KeyboardInterrupt:
if not os.path.exists(home+"/.incro_repl_history"):
histfile = open(home+"/.incro_repl_history", "w+")
for i in history:
histfile.write(i+"\n")
else:
os.remove(home+"/.incro_repl_history")
histfile = open(home+"/.incro_repl_history", "w+")
for i in history:
histfile.write(i+"\n")
sys.exit("")
When run, it get's the contents of /home/bjskistad/.incro_repl_history, reads the lines, and removes the newspace character, and then defines the _Getch class/function. Then, it runs the main loop of the script. It trys to set cur to raw_input(). I then try to sense the up arrow using the _Getch class defined. This is where I am having trouble. I can't sense the up arrow using my _Getch class. How can I sense the up arrow with my current code?
The raw_input function always read a string until ENTER, not a single character (arrow, etc.)
You need to define your own getch function, see: Python read a single character from the user.
Then you can re-implement your "input" function with a loop using getch` function.
Here is a simple usage:
while True:
char = getch()
if char == '\x03':
raise SystemExit("Bye.")
elif char in '\x00\xe0':
next_char = getch()
print("special: {!r}+{!r}".format(char, next_char))
else:
print("normal: {!r}".format(char))
Under Windows, with the following keys: Hello<up><down><left><right><ctrl+c>, you'll get:
normal: 'H'
normal: 'e'
normal: 'l'
normal: 'l'
normal: 'o'
special: '\xe0'+'H'
special: '\xe0'+'P'
special: '\xe0'+'K'
special: '\xe0'+'M'
So arrow corresponds to the combining characters: "\xe0H".
What I am trying to do is make a simple pi memorization game in Python. What I need is a way to get input from the user without having to press 'enter' after every character. It sounds like I need something like getch, but I can't get it to work. I got a getch-like function from here: https://gist.github.com/chao787/2652257#file-getch-py. I don't really understand anything that's in there. When I do 'x = getch.getch()' it says "AttributeError: '_Getch' object has no attribute 'getch'". It looks like msvcrt can do it for Windows, but I have a Mac. It also looks like curses is a thing that has getch, but it says I need to do initscr first, but then I get the error "File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/curses/__init__.py", line 30, in initscr
fd=_sys.__stdout__.fileno())
_curses.error: setupterm: could not find terminal".
This is my file just using input, where you would have to press enter every time (I actually put in 1000 digits, not an ellipsis).
pi = '3.1415926535...'
def main():
print('Welcome to PiGame!')
pigame()
while True:
yn = input('Play again? y/n ')
if yn == 'y':
pigame()
else: return
def pigame():
n=0
print('Go!')
while n<=1000:
x = input()
if x == pi[n]:
n += 1
else:
print('I\'m sorry. The next digit was '+pi[n]+'.')
print('You got to '+str(n)+' digits!')
return
print('You got to 1000! Hooray!')
You can define your own version of getch using the termios, sys and tty packages:
def getch():
import termios
import sys, tty
def _getch():
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
try:
tty.setraw(fd)
ch = sys.stdin.read(1)
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
return ch
return _getch()
This is a tested (on RPi, Py 3) code that can read a specified length of chars without need to hit Enter button
But consider one thing :
This must run on terminal otherwise raises an error
import termios, sys , tty
def _getch():
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
try:
tty.setraw(fd)
ch = sys.stdin.read(1) #This number represents the length
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
return ch
getch = _getch()
print(getch)
I've been browsing a long time searching an answer to this.
I'm using Python 2.7 in Unix.
I have a continuous while loop and I need an option where user could interrupt it, do something and after that the loop would continue.
Like:
while 2 > 1:
for items in hello:
if "world" in items:
print "hello"
else:
print "world"
time.sleep(5)
here user could interrupt the loop with pressing "u" etc. and modify elements inside he loop.
I started testing out with raw_input, but since it prompts me out every cycle, it's something that I don't need.
I tried methods mentioned here:
Keyboard input with timeout in Python
couple of times, but none of those seem to work how I wish.
>>> try:
... print 'Ctrl-C to end'
... while(True):
... pass
... except KeyboardInterrupt, e:
... print 'Stopped'
... raise
...
Ctrl-C to end
Stopped
Traceback (most recent call last):
File "<stdin>", line 2, in <module>
KeyboardInterrupt
>>>
Obviously you need to replace pass with whatever you are doing and print with the aftermath.
Here's how to do it by polling stdin:
import select, sys
p = select.poll()
p.register(sys.stdin, 1) #select the file descriptor,
#in this case stdin, which you want the
#poll object to pay attention to. The 1 is a bit-mask
#indicating that we only care about the POLLIN
#event, which indicates that input has occurred
while True:
for items in hello:
if "world" in items:
print "hello"
else:
print "world"
result = p.poll(5) #this handles the timeout too
if len(result) > 0: #see if anything happened
read_input = sys.stdin.read(1)
while len(read_input) > 0:
if read_input == "u":
#do stuff!
read_input = sys.stdin.read(1) #keep going
#until you've read all input
Note: This probably wouldn't work in Windows.
You could do nested while loops, something structured like this:
while true:
go = True
while go:
for items in hello:
if "u" in items:
go = False
else if "world" in items:
print "hello"
else:
print "world"
#Here you parse input to modify things in the nested loop, include a condition to set
#go back to true to reenter the loop
import sys
import os
import time
import termios
import tty
import fcntl
import errno
KEY = "u"
def read_characters(f):
fd = f.fileno()
# put descriptor in non-blocking mode
flags = fcntl.fcntl(fd, fcntl.F_GETFL)
fcntl.fcntl(fd, fcntl.F_SETFL, flags | os.O_NONBLOCK)
try:
while 1:
try:
yield f.read(1)
except IOError as e:
if e.errno == errno.EAGAIN:
# no more characters to read
# right now
break
finally:
# restore blocking mode
fcntl.fcntl(fd, fcntl.F_SETFL, flags)
def main():
fd = sys.stdin.fileno()
# save current termios settings
old_settings = termios.tcgetattr(fd)
# tty sets raw mode using termios module
tty.setraw(fd)
try:
while True:
time.sleep(1)
for c in read_characters(sys.stdin):
if c == KEY: break
else:
c = None
if c == KEY: break
sys.stdout.write("still going\r\n")
finally:
# restore terminal settings
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
if __name__ == "__main__":
main()