[SOLVED] Linux server: How do I use nohup make sure job is working?

Issue

What I know and what I've tried: I have a script in R (called GAM.R) that I want to run in the background that outputs .rdata, .pdf, and .jpg files. Running this from the command line is relatively simple:

$ Rscript GAM.R

However, this code takes a very long time to run so I would love to send it to the background and let it work even after I have logged out and turned the computer off. I understand this is pretty easy, as well, and my code would look like this:

$ nohup Rscript GAM.R >/dev/null 2>&1 &

I used this to see if it was working:

$ fg
nohup Rscript GAM.R > /dev/null 2>&1

The problem: I don't know how to check if the code is working (is there a way I can see its progress?) and I don't know where the outputs are going. I can see the progress and output with the first code so I must not be too far off. It doesn't seem that the second code's outputs are going where the first code's outputs went.

Solution

Your command line is diverting all output to /dev/null aka, The Bit Bucket.

Consider diverting it to a temporary file:

   $ nohup Rscript GAM.R >/tmp/GAM.R.output 2>&1 &

Then you can tail /tmp/GAM.R.output to see the results, it will show the last 10 lines of the file by default. You can use tail -f to show the end of the file, plus new output in real time.

Note, the /tmp/ filesystem is not guaranteed to exist between reboots. You can put the file somewhere else (like ~/GAM.R.output if you need to be sure.

Note, however, that if you turn your computer off, then all processing gets aborted. For this to work your machine must continue to run and not go to sleep, or shutdown.

Answered By - Greg Tarsa

Answer Checked By - David Marino (WPSolving Volunteer)