I think there is unique separate behaviour for the Pty. The system terminates if the last data is written The system terminates if the child exits (broken pipe?) The code relies on the pipe existing long enough to send the data through, but the child exiting may cause the virtual channel to be deleted before … Read more
Streams are blocking by default. TCP/IP streams, filesystem streams, pipe streams, they are all blocking. When you tell a stream to give you a chunk of bytes it will stop and wait till it has the given amout of bytes or till something else happens (an interrupt, an end of stream, an error). The operating … Read more
Like this? % ./challenge.py >stdout 2>stderr % cat stdout This is a real tty 🙂 standard output data % cat stderr standard error data Because I cheated a little bit. 😉 % echo $LD_PRELOAD /home/karol/preload.so Like so… % gcc preload.c -shared -o preload.so -fPIC I feel dirty now, but it was fun. 😀 % cat … Read more
PTY allocation request failed on channel 0 There is a limit of 256 pseudo terminals on a system. Maybe you have an application that is leaking pseudo terminals. Use lsof /dev/pts/* to see what processes have open pseudo-terminals shell request failed on channel 0 I was getting this error (without PTY allocation error). It turns … Read more
The -t option goes to how Unix/Linux handles terminal access. In the past, a terminal was a hardline connection, later a modem based connection. These had physical device drivers (they were real pieces of equipment). Once generalized networks came into use, a pseudo-terminal driver was developed. This is because it creates a separation between understanding … Read more