log4sh is an advanced logging framework for shell scripts (eg. sh, bash) that works similar to the logging products available from the Apache Software Foundataion (eg. log4j, log4perl).
log4sh provides different releases so that users can depend on functionality within a release series. It uses a variant of the X.Y.Z Semantic Versioning system.
log4sh was originally hosted on Source Forge as https://sourceforge.net/p/log4sh/. It moved here in Sep 2017 to be hosted alongside the other projects by @kward (https://github.com/kward).
2021-12-12 log4sh is not Log4Shell. log4sh is written in pure shell code, and does not use Java in any way, shape, or form. It is therefore not vulnerable to the Log4j exploit mentioned in CVE-2021-4428, which is also named Log4Shell or LogJam. For more information, about the unrelated exploit, see https://www.kaspersky.com/blog/log4shell-critical-vulnerability-in-apache-log4j/43124/.