nm is a command line utility that displays a name list from a symbol table.

It’s often useful to know if a dynamic library has a particular function or functions related to some feature.

On MacOS

-- Display only global (external) symbols
nm -g /usr/lib/libcrypto.44.dylib

-- Display only global (external) symbols, skip undefined symbols
nm -gU /usr/lib/libcrypto.44.dylib

-- Check if EVP_DigestSign is included in the library
nm -g /usr/lib/libcrypto.44.dylib | grep EVP_DigestSign