The problem i encountered is pretty simple. I tried spawning bash via runuser, after using root user for some configuration. But when I run runuser -l user -c 'bash', and then press CRTL+C, instead of interrupting whatever command I ran inside of the bash, it kills the rununser shell Session terminated, killing shell....
How can I create interactive shell without (ideally using runuser) without it being killed by CTRL+C?
Related
I'm trying to execute the command:
ssh nvidia#ubuntu-ip-address "/opt/ads2/arm-linux64/bin/ads2 svcd&"
This works so far except that it hangs in the remote terminal when "/opt/ads2/arm-linux64/bin/ads2 svcd&" is executed, unless i enter ctrl+c. So I'm looking for a command that, after executing the command, exits from the remote terminal and continue executing the local bash script.
thanks in advance
When you run a command in background on a terminal, regardless of weather it be local or remotely, if you attempt to logout most systems will warn you have running jobs. One further attempt to logout and your jobs get killed as you exit.
In order to avoid this you need to detach your running jobs from terminal.
if job is already running you can
disown -h <jobspec ar reported by jobs>
If you want to run something in background and then exit leaving it running you can use nohup
nohup command &
This is certainly ok on init systems ... not sure if it works exactly like this on systems that use systemd.
I have a script that executes a sudo command that runs a script that executes a binary (java). That binary seems to receive SIGHUP when the the login session ends (I run my script in an SSH session from my laptop, so network disconnects when I commute). The SIGHUP causes the binary process to abort.
I tried calling the sudo command with 'nohup' and trapping SIGHUP, with no success. I can't change the sudo command (e.g. 'sudo nohup' instead of 'nohup sudo'), or the script I execute with it (due to security constraints).
What other options exist? I know I can do a double fork, but I want the binary to run in the foreground while the session is live (it is running a query, so when the session is alive, I want to be able to wait for it to finish interactively and see results, but if I hangup, to have it continue to run)
So it's easy to detach applications if you're calling them directly using something like
myapplication &
But what if I want to call myapplication which then forks off 100 mychildapplication processes? Well, apparently the same command still works. I can run it, exit the terminal, and see that the child processes are still there.
It gets complicated when I introduce a Docker container.
If I were to run docker exec -it --user myuser mycontainer sh -c 'source ~/.bashrc; cd mydir; ./myapplication myarg' in a Docker container, the child processes get killed right away. I can hack it by appending a sleep 10000000 but of course then my terminal will hang indefinitely.
I can also use nohup, but then I don't get the stdout. disown does not work because it's not running in the background.
My workaround right now is using jpetazzo:nsenter, but I don't want to type my password when I run the command.
Note: the reason I have all this sudo stuff is because exec doesn't source bashrc. I can hack it by manually sourcing bashrc and it would work. It doesn't really impact what I'm trying to do.
TLDR: I want myapplication to print to my terminal, finish executing, and have the child processes stick around after I exit, all in a Docker container. The only way this can happen is if somehow I can "nohup" all processes associated with my terminal.
I'm working on a startup script that is initiated from rc.local. I start up several programs with
screen -d -m my-prog
and that works great. However, if one of the programs has problems and exits, so does the session. I'd like to be able to have the session stick around so I can attach to it and see the output from the program before it crashed.
Is there a way to do this? I thought about
screen -d -m bash -c my-prog
But again, if my-prog terminates then so does bash and then so does screen.
You can follow the answer at https://unix.stackexchange.com/questions/47271/prevent-gnu-screen-from-terminating-session-once-executed-script-ends
They suggest something like you were trying in your second attempt, but instead of using bash to invoke the command (which terminates with the command as you noted), invoke bash after the command finishes like:
screen -dmS session_name sh -c 'my-prog; exec bash'
As far as I understood from the books and bash manuals is that. When a user logs out from bash all the background jobs that is started by the user will automatically terminate, if he is not using nohup or disown. But today I tested it :
Logged in to my gnome desktop and accessed gnome-terminal.
There are two tabs in the terminal and in one I created a new user called test and logged in as test
su - test
started a script.
cat test.sh
#!/bin/bash
sleep 60
printf "hello world!!"
exit 0
./test.sh &
After that I logged out of test and closed the tab
In the next tab I exected ps aux as root and found that job is still running.
How this is happening ?
Whether running background jobs are terminated on exit depends on the shell. Bash normally does not do this, but can be configured to for login shells (shopt -s huponexit). In any case, access to the tty is impossible after the controlling process (such as a login shell) has terminated.
Situations that do always cause SIGHUP include:
Anything in foreground when the tty is closed down.
Any background job that includes stopped processes when their shell terminates (SIGCONT and SIGHUP). Shells typically warn you before letting this happen.
huponexit summary:
On: Background jobs will be terminated with SIGHUP when shell exits
$ shopt -s huponexit
$ shopt huponexit
huponexit on
Off: Background jobs will NOT be terminated with SIGHUP when shell exits.
$ shopt -u huponexit
$ shopt huponexit
huponexit off
Only interactive shells kill jobs when you close them. Other shells (for example those you get by using su - username) don't do that. And interactive shells only kill direct subprocesses.