Unable to fake terminal input with termios.TIOCSTI

Question

Most of the code samples I\'ve seen are trying to read from stdin without local echo. To do this they modify the \"local modes\" flag to remove the setting to \"Echo input c

Answer 1

TIOCSTI is an ioctl (documented in tty_ioctl(4)), not a terminal setting, so you can't use tcsetattr() -- you need to feed each character of the fake input to ioctl() instead. Never had to do ioctl's from Python before, but the following seems to work for running an ls in a different terminal (specified as the argument, e.g. /dev/pts/13) that's running Bash:

import fcntl
import sys
import termios

with open(sys.argv[1], 'w') as fd:
    for c in "ls\n":
        fcntl.ioctl(fd, termios.TIOCSTI, c)

TIOCSTI requires root privileges (or CAP_SYS_ADMIN to be more specific, but that's usually the same in practice) by the way -- see capabilities(7).