===BPCTL===

**bpctl** may be used to command a node to enter a new state, or to change permissions to use a node.

    * **bpctl** -S //<nodespec>// -s //<state>//
      State may be:
          * reboot (node will reboot immediatly)
          * halt (node halts)
          * unavailable (only root may access the node)
          * error (only root may access node) 
    * bpctl -v : print software version and exit.
    * bpctl -h : show command help.
    * bpctl <mode option>
      where mode option is one of:
          * -m <mode> <nodespec> where mode in octal (like a file mode)
          * -g <group> <nodespec> where group is a user group
          * -u <user> <nodespec> where user is a particular user that owns the node 

==Mode==

Each slave node in the cluster is owned by a user and a group, and has an access mode. This is exactly like **POSIX** file permissions except that currently, only execute has meaning to the system. Thus, **bpctl** with -m, -u, or -g is like chmod, chown, and chgrp respectivly. These permissions come into play whenever a process attempts to migrate to another node in the cluster. This mechanism is primarily useful to enforce fair sharing or support reservations in a large cluster administrativly.