The screen command

There are occasions when you have a long running process and don’t want the job to end as soon as you logout. Enter the screen command.

To start, run

screen

Run your job, type your commands, run your perl script, etc. Then detach your session with Ctrl-a d.

You can then logout of the system, but your program is still running. To reattach assuming there’s only one screen session

screen -r

To list all screen sessions

screen -ls

The command key for screen is Ctrl-a, followed by your command. To get the help for instance:
Ctrl-a ?

graph margins

To set the margins on a plot (especially helpful when using layout()), you can set par margins like this:

par(mar=c(5.1,4.1,4.1,2.1)

This is the default and indicates the number of lines of text for the bottom, left, top and right margins respecitvely.

For multipanel plots, I have had success using

par(mar=c(2,2,2,2))

You can see the margin settings by using

par("mar")

A similar function par(“mai”) specifies the number of lines in inches.

Reference
http://www.r-bloggers.com/setting-graph-margins-in-r-using-the-par-function-and-lots-of-cow-milk/