How to make a script wait for a pressed key

Question

I want my script to wait until the user presses any key  How do I do that

User · Answer

The python manual provides the following:

import termios, fcntl, sys, os
fd = sys.stdin.fileno()

oldterm = termios.tcgetattr(fd)
newattr = termios.tcgetattr(fd)
newattr[3] = newattr[3] & ~termios.ICANON & ~termios.ECHO
termios.tcsetattr(fd, termios.TCSANOW, newattr)

oldflags = fcntl.fcntl(fd, fcntl.F_GETFL)
fcntl.fcntl(fd, fcntl.F_SETFL, oldflags | os.O_NONBLOCK)

try:
    while 1:
        try:
            c = sys.stdin.read(1)
            print "Got character", repr(c)
        except IOError: pass
finally:
    termios.tcsetattr(fd, termios.TCSAFLUSH, oldterm)
    fcntl.fcntl(fd, fcntl.F_SETFL, oldflags)

which can be rolled into your use case.

User · Answer

One way to do this in Python 2  is to use raw input     raw input  Press Enter to continue        In python3 it s just input

User · Answer

I don t know of a platform independent way of doing it  but under Windows  if you use the msvcrt module  you can use its getch function   import msvcrt c   msvcrt getch   print  you entered   c   mscvcrt also includes the non-blocking kbhit   function to see if a key was pressed without waiting  not sure if there s a corresponding curses function    Under UNIX  there is the curses package  but not sure if you can use it without using it for all of the screen output   This code works under UNIX   import curses stdscr   curses initscr   c   stdscr getch   print  you entered   chr c  curses endwin     Note that curses getch   returns the ordinal of the key pressed so to make it have the same output I had to cast it

User · Answer

Cross Platform  Python 2 3 code     import sys  os  def wait key            Wait for a key press on the console and return it          result   None     if os name     nt           import msvcrt         result   msvcrt getch       else          import termios         fd   sys stdin fileno            oldterm   termios tcgetattr fd          newattr   termios tcgetattr fd          newattr 3    newattr 3   amp   termios ICANON  amp   termios ECHO         termios tcsetattr fd  termios TCSANOW  newattr           try              result   sys stdin read 1          except IOError              pass         finally              termios tcsetattr fd  termios TCSAFLUSH  oldterm       return result   I removed the fctl non-blocking stuff because it was giving IOErrors and I didn t need it   I m using this code specifically because I want it to block       Addendum   I implemented this in a package on PyPI with a lot of other goodies called console    gt  gt  gt  from console utils import wait key   gt  gt  gt  wait key    h

User · Answer

I am new to python and I was already thinking I am too stupid to reproduce the simplest suggestions made here  It turns out  there s a pitfall one should know   When a python-script is executed from IDLE  some IO-commands seem to behave completely different  as there is actually no terminal window    Eg  msvcrt getch is non-blocking and always returns  ff  This has already been reported long ago  see e g  https   bugs python org issue9290   - and it s marked as fixed  somehow the problem seems to persist in current versions of python IDLE   So if any of the code posted above doesn t work for you  try running the script manually  and NOT from IDLE

User · Answer

In Python 3 use input     input  Press Enter to continue        In Python 2 use raw input         raw input  Press Enter to continue        This only waits for the user to press enter though    One might want to use msvcrt   Windows DOS only  The msvcrt module gives you access to a number of functions in the Microsoft Visual C C   Runtime Library  MSVCRT     import msvcrt as m def wait        m getch     This should wait for a key press   Additional info   in Python 3 raw input   does not exist  In Python 2 input prompt  is equivalent to eval raw input prompt

User · Answer

If you want to see if they pressed a exact key  like say  b   Do this   while True      choice   raw input   gt          if choice     b            print  You win          input  yay           break

User · Answer

If you want to wait for enter  so the user knocking the keyboard does not cause something un-intended to happen  use  sys stdin readline

User · Answer

If you are ok with depending on system commands you can use the following  Linux and Mac OS X  import os os system  read -s -n 1 -p  quot Press any key to continue    quot    print    Windows  import os os system  quot pause quot

User · Answer

os system seems to always invoke sh  which does not recognize the s and n options for read  However the read command can be passed to bash     os system    bash -c  read -s -n 1 -p  Press any key to continue

User · Answer

Simply using  input  Press Enter to continue        will cause a SyntaxError  expected EOF while parsing   Simple fix use   try      input  Press enter to continue   except SyntaxError      pass

User · Answer

On my linux box  I use the following code  This is similar to code I ve seen elsewhere  in the old python FAQs for instance  but that code spins in a tight loop where this code doesn t and there are lots of odd corner cases that code doesn t account for that this code does   def read single keypress           Waits for a single keypress on stdin       This is a silly function to call if you need to do it a lot because it has     to store stdin s current setup  setup stdin for reading single keystrokes     then read the single keystroke then revert stdin back after reading the     keystroke       Returns a tuple of characters of the key that was pressed - on Linux       pressing keys like up arrow results in a sequence of characters  Returns         x03    on KeyboardInterrupt which can happen when a signal gets     handled               import termios  fcntl  sys  os     fd   sys stdin fileno         save old state     flags save   fcntl fcntl fd  fcntl F GETFL      attrs save   termios tcgetattr fd        make raw - the way to do this comes from the termios 3  man page      attrs   list attrs save    copy the stored version to update       iflag     attrs 0   amp     termios IGNBRK   termios BRKINT   termios PARMRK                     termios ISTRIP   termios INLCR   termios  IGNCR                     termios ICRNL   termios IXON         oflag     attrs 1   amp    termios OPOST       cflag     attrs 2   amp     termios CSIZE   termios  PARENB      attrs 2     termios CS8       lflag     attrs 3   amp     termios ECHONL   termios ECHO   termios ICANON                     termios ISIG   termios IEXTEN      termios tcsetattr fd  termios TCSANOW  attrs        turn off non-blocking     fcntl fcntl fd  fcntl F SETFL  flags save  amp   os O NONBLOCK        read a single keystroke     ret          try          ret append sys stdin read 1     returns a single character         fcntl fcntl fd  fcntl F SETFL  flags save   os O NONBLOCK          c   sys stdin read 1    returns a single character         while len c   gt  0              ret append c              c   sys stdin read 1      except KeyboardInterrupt          ret append   x03       finally            restore old state         termios tcsetattr fd  termios TCSAFLUSH  attrs save          fcntl fcntl fd  fcntl F SETFL  flags save      return tuple ret

[python] How to make a script wait for a pressed key?

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