ClusterShell is an event-driven open source Python library designed to run local or remote commands in parallel on server farms and large Linux clusters. It handles typical HPC cluster administration tasks: operating on groups of nodes, executing distributed commands with optimized algorithms, gathering and merging output, and collecting return codes. ClusterShell leverages remote shell facilities already present on your systems, such as SSH, and provides clush, clubak, and nodeset — convenient command-line tools for interactive use and shell scripts. It supports Python 2 and 3, and is distributed under the LGPL v2.1+ license.