Shell – “nohup sudo …” does not prompt for passwd and does nothing

If you just want to write a single y to the stdin of the process, you can do this:

(echo y | nohup myprocess) &

If you want to keep writing y for every prompt that comes up, the coreutil yes exists for exactly this purpose -- it will keep writing whatever you tell it to to stdout. Its default is to output "y", so you can just:

(yes | nohup myprocess) &

but if you need something else you can pass it as an argument

It's a little hard to diagnose, as you don't give source for myproc, but I suspect that your problem has something to do with "controlling TTY". I wrote a small shell script that just calls sleep 100. I ran it under nohup:

$ nohup ./sleeper > sleeper.out &

[1] 25305
-bash-3.2$ jobs
[1]+  Running                 nohup ./sleeper > sleeper.out &
-bash-3.2$ ps -l -p 25305
F S   UID   PID  PPID  C PRI  NI ADDR SZ WCHAN  TTY          TIME CMD
0 S 429624 25305 18252  0 77   0 - 15961 wait   pts/0    00:00:00 sleeper

If you look at the ps output, you see a column named "TTY". At least some versions of nohup (the one I used above is from GNU coreutils, version 5.97, so relatively old). When I exited the bash shell from which I started sleeper, the TTY column changed to '?', meaning that sleeper didn't have one.

If myproc doesn't deliberately detach itself from it's controlling TTY, it's still possible to get things like a SIGPIPE signal if it tries to write to stdout. It seems to me other things are possible, but I can't recall or google anything up.

If you can find or compile "daemonize", you might want to try it. If myproc is compiled, you could modify the source to call the daemon(3) library function.