The following directories are not writable by your user: /usr/local/bin You should change the ownership of these directories to your user. sudo chown -R zwen /usr/local/bin And make sure that your user has write permission. chmod u+w /usr/local/bin

lcov 2.4_1 is already installed and up-to-date. To reinstall 2.4_1, run: brew reinstall lcov

You are using macOS 12. We (and Apple) do not provide support for this old version. You may have better luck with MacPorts which supports older versions of macOS: https://www.macports.org This is a Tier 3 configuration: https://docs.brew.sh/Support-Tiers#tier-3 You can report issues with Tier 3 configurations to Homebrew/* repositories! Read the above document before opening any issues or PRs.