I can run a local script on a remote server using the -s option, like so:
# run a local script without nohup...
ssh $SSH_USER#$SSH_HOST "bash -s" < myLocalScript.sh;
And I can run a remote script using nohup, like so:
# run a script on server with nohup...
ssh $SSH_USER#$SSH_HOST "nohup bash myRemoteScript.sh > results.out 2>&1 &"
But can I run my local script with nohup on the remote server? I expect the script to take many hours to complete so I need something like nohup. I know I can copy the script to the server and execute it but then I have to make sure I delete it once the script is complete, would rather not have to do that if possible.
I've tried the following but it's not working:
# run a local script without nohup...
ssh $SSH_USER#$SSH_HOST "nohup bash -s > results.out 2>&1 &" < myLocalScript.sh;
You shouldn't have to do anything special - Once you kick off a script on another machine, it should finish running even if you terminate the connection:
For example
ssh $SSH_USER#$SSH_HOST "bash -s > results.out 2>&1" < myLocalScript.sh &
# Please wait a few seconds for the connection to be established
kill $! # Optional: Kill the last process
If you want to test it, try a simple script like this
# myLocalScript.sh
echo 'File created - sleeping'
sleep 30
echo 'Finally done!'
The results.out file should immediately be created on the other machine with "File created - sleeping" in it. You can actually kill the local ssh process with kill <your_pid>, and it will still keep running on the other machine, and after 30 seconds, print "Finally done!" into the file, and exit.
Related
I am building a rest API with java, when the endpoint gets called. I will spawn a virtual shell with RunTime.getRuntime().exec(My_script.sh)
My script then proceeds to ssh into a server, create some files, and most importantly... I needs to run a script that sits on that server to process the files.
I run the command with
nohup myscript.sh > /dev/null/ 2>&1 &
I also added sleep 5 because i read that nohup may take a second to get things started
The script runs until the shell disconnects and dies.
So as of now
java application launches a shell
the bash script initiates a ssh connection and creates a subshell that runs a secondary script
while in the subshell, with our second script, we create some files and then we call nohup script to start the script
subshell exits and terminates
main shell exits and terminates
script we called disconnects and never finishes running
Some things I have tried
I have tried calling the script from the ssh connection,
psudo example
ssh user#host "nohup script.sh > /dev/null/ 2>&1 &"
also tried with different quotes
ssh user#host "nohup script.sh > /dev/null/" 2>&1 &
Another thing I can potentially do is keep the initial shell open. So that the script wont die when it disconnects... because it never will
I have looked into to other options like screen but I don't think it will be useful if the machine that initiated the script gets completely terminated after it starts
Things to note
I don't have control over the Linux box I ssh into, so I cannot install packages on that machine. I can however install packages on my shell
I'm stuck with an exercise. I'm writing a bash script where I need to start execution of bash script on a remote machine and then instantly continue scripts execution. I have tried using this:
ssh user#host 'nohup bash -s > /dev/null 2>&1&' < local_script.sh
This however seems to be doing nothing. I have searched the web and can't find answer. All help will be highly appreciated.
I think you need to leave the ssh session open for this to work properly. If the ssh session closes then the remote process looses it's stdin. So bash won't be able to read load_script.sh before ssh closes.
ssh user#host 'bash -s > /dev/null 2>&1' < local_script.sh &
Anything else requires you to send the script first, then kick it off.
I have a shell script that is used to setup the network settings on a linux machine in bash, it will mainly be used over SSH. Here are the last few lines of the script.
service network stop
rm -rf $NETWORKFILE
touch $NETWORKFILE
echo NETWORKING=yes > $NETWORKFILE
echo HOSTNAME=$HOSTNAME >> $NETWORKFILE
mv $ETHFILE /etc/sysconfig/network-scripts/ifcfg-eth0
service network start
As you can see, to apply the network settings it has to stop then start the network and apply the settings while the network is down. This would then cause the SSH session to be disconnected on the first line of the code I have shown and the script to thus stop and the settings to not be applied. How can I have the shell script run these last few lines after the SSH session is disconnected that started the shell script? Also, it needs to be done in the code and not through a screen or nohup command when starting the script.
Try completely disconnecting the script from the terminal, by redirecting all standard streams and putting it in background:
nohup script < /dev/null > script.log 2>&1 &
Also you can put "sleep 2" as the first line of the script, so that after putting the script in background, you can quickly disconnect cleanly, before the server closes it forcibly. This is just for convenience.
Maybe if you get your script PID, and then disown the process after stopping the network, your script will continue running after the ssh session is disconnected.
./script &
pid=$$
disown -h $pid
service network stop
rm -rf $NETWORKFILE
touch $NETWORKFILE
echo NETWORKING=yes > $NETWORKFILE
echo HOSTNAME=$HOSTNAME >> $NETWORKFILE
mv $ETHFILE /etc/sysconfig/network-scripts/ifcfg-eth0
service network start
If I run a process at the remote site by using ssh as follows:
nohup ssh remote sleep 100 &
Is there a way to know the PID of sleep at remote?
Trying echo $! just returns the PID of ssh at local.
And, greping won't work since there are multiple sleep processes at remote.
You could pass a string to ssh so try
nohup ssh remote 'sleep 100 &; echo $!'
Try the following
nohup ssh remote 'sleep 100 > out 2> err < /dev/null & echo $!'
I am using SSH to start a background process on a remote server. This is what I have at the moment:
ssh remote_user#server.com "nohup process &"
This works, in that the process does start. But the SSH session itself does not end until I hit Ctr-C.
When I hit Ctr-C, the remote process continues to run in the background.
I would like to place the ssh command in a script that I can run locally, so I would like the ssh session to exit automatically once the remote process has started.
Is there a way to make this happen?
The "-f" option to ssh tells ssh to run the remote command in the background and to return immediately. E.g.,
ssh -f user#host "echo foo; sleep 5; echo bar"
If you type the above, you will get your shell prompt back immediately, you will then see "foo" output. Five seconds later you will then see "bar" output. In the meantime, you could have been using the shell.
When using nohup, make sure you also redirect stdin, stdout and stderr:
ssh user#server 'DISPLAY=:0 nohup xeyes < /dev/null > std.out 2> std.err &'
In this way you will be completely detached from the remote process. Be carefull with using ssh -f user#host... since that will only put the ssh process in the background on the calling side. You can verify this by running a ps -aux | grep ssh on the calling machine and this will show you that the ssh call is still active, but just put in the background.
In my example above I use DISPLAY=:0 since xeyes is an X11 program and I want it started on the remote machine.
You could use screen to run your process on this screen, detach from screen Ctrl-a :detach and exit your current session without problem. Then you can reconnect to SSH and attach to this screen again to continue with your task or check if is finished.
Or you can send the command to an already running screen. Your local script should look like this:
ssh remote_user#server.com
screen -dmS new_screen sh
screen -S new_screen -p 0 -X stuff $'nohup process \n'
exit
For more info see this tutorial
Well this question is almost 10 years old, but I recently had to launch a very long script (taking several hours to complete) on a remote server and I found a way using the crontab.
If can edit your user's crontab on the remote server, connect with ssh to the server, edit the crontab and add an entry that will start your script the next minute. Let's say it's 15h03. Add this line :
4 15 * * * /path/to/your/script.sh
save your crontab, wait a minute for the script to be launched. Then edit again your crontab to remove this entry.
You can then safely exit ssh, even shut down your computer while the script is running.