The CCR computing clusters run the Linux operating system, which is a version of UNIX.  The user interface is command line.  When a user logs in to the front-end of the cluster, a login shell starts.  This is the traditional command line user interface.  Users input UNIX commands to the login shell.

The PATH environmental variable is a list of directories that is searched for a command.  In order to use a command, either it must be in your path or you must specify the complete path.

Default Login Shell:

  • The default login shell for all users is bash (GNU Bourne-Again Shell).
  • View man page for bash:   man bash
  • Users can request a different login shell by submitting a ticket to CCR Help.
  • Show default shell:   echo $SHELL
  • Check out the Bash Survival Guide attachment below

Default Path:

  • Show the default path: echo $PATH

Modifying the PATH:

  • Use modules to modify your PATH.
  • Add to the default path (bash):    export PATH=newpath:${PATH}

Environmental Variables:

  • Show the environment (bash):    env


  • Modules are used to modify paths and set variables for application packages.  Please see the Modules documentation for more information.