To run Processing in Linux, open a terminal window and execute the following:
user$ processing &
If this doesn't work, it may be that the executable is not in your path. To fix this, add the following line to your configuration file:
The configuration is your .bashrc file located in the home directory. Note - this is a hidden file. On most systems, it is necessary to force Linux to reload the configuration file before the changes will take effect. You do this using the source command:
user$ source .bashrc
You should be able to use the processing command now.