Bash: start remote python application through ssh and get its PID
bash, linux, pid, remote-access, ssh
Solution
Thanks to Kingslndian i solved it by making one single command that did the three steps i required, so with that avoided the problem of running in different shells:
ssh root@myserver 'python /root/python/run_dev_server.py > /dev/null 2>&1 & echo $! > "dmr.pid"'
Problem
I'm creating a little bash script to copy new files from a windows machine to a remote linux centos server (i run this script using the git-shell) then i want to restart the python application thats running in the server to use those new files. The problem is that everytime i run this script i want to end the actual running process before i start it again, so i want to get the pid of the process i start and save it to a file in the remote host so i can read it from there the next time i run the program and kill it. My code by now looks similar to this: ``` echo "Copying code files to server..." # The destination folder has to exist in the server scp -r ./python/ root@myserver:/root/ echo "Checking for running processes..." if ssh root@myserver 'ls dmr.pid >/dev/null'; then echo "PID file exists, reading file..." PID=$(ssh root@myserver 'cat dmr.pid') # Terminate the actual process echo "Terminating the process with PID '$PID'..." ssh root@myserver 'kill $PID' else echo "PID file doesn't exist, not known processes running" fi # Restart the server and get the PID echo "Restarting the server..." ssh root@myserver 'python /root/python/run_dev_server.py > /dev/null 2>&1 &' SERV_PID=$(ssh root@myserver 'echo $!') echo "Saving PID to file dmr.pid" ssh root@myserver "echo '$SERV_PID' > \"dmr.pid\"" echo "Sucesfully finished!" ``` The important lines are: ``` ssh root@myserver 'python /root/python/run_dev_server.py > /dev/null 2>&1 &' SERV_PID=$(ssh root@myserver 'echo $!') ``` the problem with this is that the script finishes but the file ends up empty as well as the $SERV_PID variable. And if i dont redirect the outputs and just do something like this: ``` SERV_PID=$(ssh root@myserver 'python /root/python/run_dev_server.py & echo $!') ``` i get stuck after "Restarting the server" and never get the PID or the file that will contain it or even the end of the script. But if i run this right in the console: ``` ssh root@myserver 'python /root/python/run_dev_server.py & echo $!' ``` i get a PID printed to the terminal. Any advice on this would be really appreciated.