Hitting Enter the script ends the process remains in the background.
Almost! Actually, the script has already exited by the time you press Enter. However, that's how you can get your prompt back (because your shell prints its $PS1 all over again).
The reason why hitting Ctrl + C terminates both of them is because the two of them are linked. When you execute your script, your shell initiates a subshell in which to run it. When you terminate this subshell, your background process dies, probably from a SIGHUP signal.
Separate the script, the background process and the subshell
Using nohup, you might be able to get rid of this little inconvenience.
#!/bin/sh
read -s -p "Enter Password: " pw
user=testuser
share=/fshare
cmd="sfk ftpserv -user=$user -pw=$pw -usedir $share=$share"
nohup $cmd &
The disown alternative
If you can switch from /bin/sh to /bin/bash, you can give a try to disown as well. To know more, just type help disown in a bash instance.
disown -h $cmd &
Killing the background process "nicely"
Now, when it comes to killing your process, you can perfectly do a "Ctrl + C" using kill. Just don't send a brutal SIGKILL. Instead, you could use:
$ kill -2 [PID]
$ kill -15 [PID]
Which will send a nice SIGINT (2) or SIGTERM (15) to your process. You may also want to print the PID value after starting the process:
...
nohup $cmd &
echo $!
... or even better, make the script wait for a SIGINT, and send it back to the background process (this will keep your script in the foreground though):
#!/bin/sh
read -s -p "Enter Password: " pw
user=testuser
share=/fshare
cmd="sfk ftpserv -user=$user -pw=$pw -usedir $share=$share"
nohup $cmd &
# Storing the background process' PID.
bg_pid=$!
# Trapping SIGINTs so we can send them back to $bg_pid.
trap "kill -2 $bg_pid" 2
# In the meantime, wait for $bg_pid to end.
wait $bg_pid
If a SIGINT isn't enough, just use a SIGTERM instead (15) :
trap "kill -15 $bg_pid" 2 15
This way, when your script receives a SIGINT (Ctrl + C, kill -2) or a SIGTERM while waiting for the background process, it'll just relay the signals to it. If these signals do kill the sfk instance, then the wait call will return, therefore terminating your script as well :)
Best Answer
I'm guessing the real problem here is that the command you are trying to run is Emacs. Running Emacs as root is hardly ever a good idea. Emacs also overrides a number of keystrokes, so
C-zmight not work simply for that reason. Ifrootis already logged in,emacsmight start graphically onroot's display. Etc, etc.Look at using the
sudo:method from Tramp for editing files usingsudofrom Emacs. For example, to edit/etc/motd, doC-x C-fand type the path as/sudo:root@localhost:/etc/motd.