Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
Every Hello has a response. Second TTY will send a hello to the sender TTY and vice versa:
echo 'echo hello > /dev/pts/1' > /dev/pts/0 The 1st receiver should send ‘hello’ to the original sender, but it does not. What is wrong?
[Clarification] I have two shells running. /dev/pts/1 is the initial sender.
When you send your echo command to
/dev/pts/0you are literally just sending the output of that echo to the other TTY’s output – you are not sending it to the other TTY’s input buffers. Therefore your nestedechocommand will simply be displayed on the other TTY, but not executed.There is an
ioctl()callTIOCSTIwhich can be used to fake input on another TTY, but only if you have ‘write’ permission to that other TTY.Many years ago I recall that some friends and I discovered holes on some versions of UNIX which didn’t correctly enforce the security permissions on TIOCSTI. If root had left a terminal logged in somewhere it was possible to make the root user’s terminal type in commands on your behalf…