Tutorial:
Object permissions


Table of Contents

  About object permissions
Changing object permissions

  Other relevant on-line documents:
  Logging in to a running Legion system
Legion graphical user interface
Introduction to Legion context space
Context-related commands
How to start remote programs in Legion
Sample makefile for remote programs
Object permissions
Legion tty objects
Running a PVM code in Legion
Running an MPI code in Legion
Quick list of all Legion commands
Usage of all Legion commands
Starting and shutting down Legion 1.5
Using Legion security features
Legion host and vault objects
Adding host and vault objects
The list of all on-line 1.5 tutorials


The Legion tutorials offer quick and simple instructions for various key procedures for a Legion system. More complete explanations of all of the procedures discussed here are available on separate pages, and can be found by clicking on the icon.

Depending on how your system is set up, you may need to set up your access to your system before you can run Legion commands. This will probably involve running a command such as this:

$ . ~legion/setup.sh

or

$ source ~legion/setup.csh
The exact syntax will depend on what kind of shell you are using and where your Legion files are installed (i.e., the value of ~legion will depend on your individual Legion net). Consult your system administrator for more information.


About object permissions
If your system administrator has enabled Legion security, the objects that you create while logged in cannot be used by any other users. If you wish to share your objects you will need to give other users permission to read, write, or execute objects.

For our purposes, "read" methods are defined as methods that obtain but do not modify an object's state, "write" methods are methods that modify an object's state, and "execute" methods are methods that run an object.

This command works on common Legion object types: context, file, class, tty, implementation, host, and vault objects all fall into this category.


Changing object permissions
You can use the legion_change_permissions command to give other users permission to read, write, or execute your objects. There are specific lags to add [+] or remove [-] read, write, or execute permissions on objects. So, if you wanted to allow user bob to be able to read your file object foo, you would enter:
$ legion_change_permissions +r /users/bob foo
This lets bob "read" your object foo.