Shell interpreter doesn't work after installation because the installation script creates JSR folder named "shell" when the interpreter itself is named "sh" and is looking for folder named "sh"
I found 2 workarounds for this issue:
1) rename the JARs folder to "sh"
2) add path to the "shell" folder in env variable: ZEPPELIN_INTP_CLASSPATH_OVERRIDES
It looks like it is an easy code fix