Here’s a memo on how to handle the situation when trying to install zlib with RVM and getting an error about no checksum, preventing installation.

# rvm pkg install zlib
Fetching zlib-1.2.7.tar.gz to /usr/local/rvm/archives
There is no checksum for 'http://prdownloads.sourceforge.net/libpng/zlib-1.2.7.tar.gz' or 'zlib-1.2.7.tar.gz', it's not possible to validate it.
If you wish to continue with unverified download add '--verify-downloads 1' after the command.


Please note that it's required to reinstall all installed rubies:

    rvm reinstall all --force
    rvm all-gemsets do rvm gemset pristine

You can install it by doing the following:

rvm --verify-downloads 1 pkg install zlib 
rvm get head

That’s all.

【Reference】

・ruby - RVM pkg install checksum error - Stack Overflow

That’s all from the Gemba.