Brew Caveats meaning?

Question

What does this mean when I brew install python

Caveats
A CA file has been bootstrapped using certificates from the SystemRoots
keychain. To add additional certificates (e.g. the certificates added in
the System keychain), place .pem files in
  /usr/local/etc/openssl/certs

and run
  /usr/local/opt/openssl/bin/c_rehash

This formula is keg-only, which means it was not symlinked into /usr/local.

Apple has deprecated use of OpenSSL in favor of its own TLS and crypto libraries

Generally there are no consequences of this for you. If you build your
own software and it requires this formula, you'll need to add to your
build variables:

    LDFLAGS:  -L/usr/local/opt/openssl/lib
    CPPFLAGS: -I/usr/local/opt/openssl/include

1. What are the .pem files?
2. Keg-only , does these mean I need to link brew python in my bash profile to refer to the brew installation instead of the build in mac python?

Answer 1

1. pem files are certificate files (public keys); you usually need them to verify the authenticity of the remote side when using encryption like TLS/SSL (eg https:// ). You could have tried googling for "PEM file" , which might direct you eg to What is a Pem file and how does it differ from other OpenSSL Generated Key File Formats?

2. keg-only means that the so-installed package doesn't pollute the global namespace (so you cannot acidentally use it, and break things). Probably the simplest way to use the brew-installed python is to add /usr/local/opt/python/bin/ (or similar, I don't have brew available right now) to your PATH variable in your .bashrc . ( need to link brew python doesn't make much sense in the context of a bash profile; also you should use the term symlink rather than link to avoid ambiguity)