from http://www.nas.nasa.gov/Software/PBS/pbsnashome.html and 
http://www.nas.nasa.gov/Software/PBS/summary.html :
	The Portable Batch System (PBS) project was started to create a
flexible, extensible batch processing system for heterogeneous computing
networks.  You can submit your batch job on any machine and PBS will run your
script on the machine you request when the resources you need are available.
Your PBS system administrator can define the method used to choose what jobs to
run where, and in what order.  PBS can be installed on almost any UNIX machine,
from single-processor workstations to workstation clusters and massively
parallel supercomputers.
	A typical batch queuing system has a set of queues.  Within each queue,
jobs are selected in FIFO order.  This limits the scheduling policies available
to the adminstrator.  The purpose of PBS is to provide additional controls over
initiating or scheduling execution of batch jobs, and to allow routing of jobs
between different hosts. PBS's independent scheduling module allows the
administrator to define what types of resources, and how much of each resource,
can be used by each job.  The scheduling module has full knowledge of the
available queued jobs, running jobs, and system resource usage.  Using one of
several procedural languages, the scheduling policies can easily be modified to
suit the computing requirements and goals of any site. PBS also has a mechanism 
allowing users to specify unique resources required for a job to complete.

WWW: http://pbs.mrj.com/
- David A. Bader <dbader@eece.unm.edu>