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How can I read only one character at a time?
Unix Socket FAQ for Network programming
(Continued from previous question...)
How can I read only one character at a time?
This question is usually asked by people who are testing their server
with telnet, and want it to process their keystrokes one character at
a time. The correct technique is to use a psuedo terminal (pty).
More on that in a minute.
You can have
your server send a sequence of control characters: 0xff 0xfb 0x01 0xff
0xfb 0x03 0xff 0xfd 0x0f3, which translates to IAC WILL ECHO IAC WILL
SUPPRESS-GO-AHEAD IAC DO SUPPRESS-GO-AHEAD. For more information on
what this means, check out std8, std28 and std29. Roger also gave the
following tips:
o This code will suppress echo, so you'll have to send the characters
the user types back to the client if you want the user to see them.
o Carriage returns will be followed by a null character, so you'll
have to expect them.
o If you get a 0xff, it will be followed by two more characters.
These are telnet escapes.
Use of a pty would also be the correct way to execute a child process
and pass the i/o to a socket.
(Continued on next question...)
Other Interview Questions
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