The CHOS software package combines a Linux kernel module, a
PAM module, and batch system integration to provide a mechanism
for concurrently supporting multiple Linux environments on a
single Linux system. This presentation gives an introduction to
CHOS and details how NERSC has deployed this utility on the PDSF
HPC system to meet the complex, and often conflicting, software
environment requirements of multiple applications. The CHOS
utility has been in continuous use on PDSF for over 8 years, and
has proven to be a robust and simple approach to ensure optimal
software environments for HENP workloads.
 CHOS was written by Shane Canon of NERSC, and the code is
available on GitHub. The CHOS technology is explained in
detail in the paper at .