bash

Unix has the ability to run your program in the background. This means that instead of waiting for the program to finish execution, the UNIX shell prompts you again and you can run other commands at the same time that the background process is running. To run the program myprog in background, type:

myprog &

The shell will respond with a number, its process identification number (or PID) and then return to the prompt.

More generally, you can use nohup to leave a big job running in the background even after you logout. For example, to keep the program myprog running in background, type:

nohup myprog &

For example, to run your R job in the background:

nohup R CMD BATCH --no-save code.R code.log &

With a Matlab job, where we redirect the output to outfile.txt and the error messages to error.txt:

nohup matlab -nodesktop -nodisplay < infile.m > outfile.txt 2> error.txt &

screen

You may alternatively choose to use GNU screen to run your jobs so that you can leave them running when you logout. Just invoke screen from your shell, type a space or carriage return to dismiss the startup message, then start your job. When you want to detach, type Control-a followed by Control-d. You can then exit from your terminal session. When you want to access your job again, connect to the same machine your job is running on and type screen -r. Note that screen is likely to be more robust than nohup in terms of ensuring your job is not killed by ending a remote login session abruptly (e.g., closing your laptop, losing your wireless connection, etc.).

A few more details on screen. To see a list of available sessions, do screen -ls. To start a session with a specific name, you can do screen -S sessionName. Then to resume a named session, do screen -r SessionName. Or to resume a particular unnamed session, use the name reported by screen -ls, e.g., it might look something like 4763.pts-2.beren. If a session is in use, you can forcibly detach it from the other location and attach to it by doing screen -d -R sessionName. To close a session, you can use exit from within the session.