ROOT First steps

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How to start ROOT

ROOT is installed on our computers, but it is not setup by default, so you will get an error when typing "root" at the command line. What you need to do is

module load root

first, then you can type

root -l

to start ROOT (the option -l suppresses the splash screen -- try without to see what you missed). (The module system provides a number of applications and also different versions of ROOT. Type module avail (outside ROOT) to view a list.)

ROOT has a command line which greets you with something like

root [0] 

To quit ROOT, type


(You can use more than one q, e.g. .qqq, to try harder to quit ROOT which might be necessary in case you messed up ROOT's memory.)

How to setup ROOT by default

Normally, you would need to type module load root whenever you start a new terminal. If you find this too cumbersome on the long term, there is a way around by adding a line to your shell start-up script: Using your favorite text editor, create a new file (or open it if it exists) called ~/.bashrc and put module load root into it. This will execute the module command whenever you start a new terminal. (The tilde ~ in the filename refers to your home directory. The file needs to be stored there. Its filename .bashrc starts with a dot, so that it is hidden. Type ls -a to list hidden files with the ls command.)

Useful commands

At some point you will need to setup a specific root version.

To get an commented overview over the installed versions, type:

 module help root/versions

The internal command for the module system is:

 module avail root -t

To get detailed information on a certain version type e.g. (known issues will be highlighted in red):

 module help root/5.34.36

In case of problems or questions please contact

Further reading

  • There is some nice introductory course here (in German).
    • The part on ROOT starts here.