(I'm using bash 4.4.12 on Debian 8) Please follow the following steps to reproduce.
>From tty #1: $ tty /dev/pts/11 $ ssh -o ControlMaster=yes -o ControlPath=/tmp/socket.tmp -N -f 127.0.0.1 root@127.0.0.1's password: $ ps -C ssh uw USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 716 0.0 0.2 44428 692 ? Ss 22:04 0:00 ssh -o ControlMaster=yes -o ControlPath=/tmp/socket.tmp -N -f 127.0 $ $ ssh -o ControlMaster=no -o ControlPath=/tmp/socket.tmp 127.0.0.1 sleep 9999 & [1] 725 $ <-- Then I cannot input anything except CTRL-C Go to tty #2: $ ps t pts/11 jw PPID PID PGID SID TTY TPGID STAT UID TIME COMMAND 32714 725 725 32714 pts/11 32714 S 0 0:00 ssh -o ControlMaster=no -o ControlPath=/tmp/socket.tmp 127.0.0.1 sleep 9999 579 32714 32714 32714 pts/11 32714 Ss+ 0 0:00 bash $ If I kill the "ssh -o ControlMaster=no -o ControlPath=/tmp/socket.tmp 127.0.0.1 sleep 9999" then tty #1 (pts/11) would be able to accept my input again. Seems like the background "ssh" at tty #1 is consuming all input. I cannot understand this since it should be stopped by SIGTTIN if it tries to read from the tty. Idea? -clark
