How to get the process ID to kill a nohup process?

When using nohup and you put the task in the background, the background operator (&) will give you the PID at the command prompt. If your plan is to manually manage the process, you can save that PID and use it later to kill the process if needed, via kill PID or kill -9 PID (if you need to force kill). Alternatively, you can find the PID later on by ps -ef | grep "command name" and locate the PID from there. Note that nohup keyword/command itself does not appear in the ps output for the command in question.

If you use a script, you could do something like this in the script:

nohup my_command > my.log 2>&1 &echo $! > save_pid.txt

This will run my_command saving all output into my.log (in a script, $! represents the PID of the last process executed). The 2 is the file descriptor for standard error (stderr) and 2>&1 tells the shell to route standard error output to the standard output (file descriptor 1). It requires &1 so that the shell knows it's a file descriptor in that context instead of just a file named 1. The 2>&1 is needed to capture any error messages that normally are written to standard error into our my.log file (which is coming from standard output). See I/O Redirection for more details on handling I/O redirection with the shell.

If the command sends output on a regular basis, you can check the output occasionally with tail my.log, or if you want to follow it "live" you can use tail -f my.log. Finally, if you need to kill the process, you can do it via:

kill -9 `cat save_pid.txt`rm save_pid.txt

I am using red hat linux on a VPS server (and via SSH - putty), for me the following worked:

First, you list all the running processes:

ps -ef

Then in the first column you find your user name; I found it the following three times:

• One was the SSH connection
• The second was an FTP connection
• The last one was the nohup process

Then in the second column you can find the PID of the nohup process and you only type:

kill PID 

(replacing the PID with the nohup process's PID of course)

And that is it!

I hope this answer will be useful for someone I'm also very new to bash and SSH, but found 95% of the knowledge I need here :)

suppose i am running ruby script in the background with below command

nohup ruby script.rb &

then i can get the pid of above background process by specifying command name. In my case command is ruby.

ps -ef | grep ruby

output

ubuntu   25938 25742  0 05:16 pts/0    00:00:00 ruby test.rb

Now you can easily kill the process by using kill command

kill 25938