error installing psycopg2, library not found for -

问题:

I run "sudo pip install psycopg2" and I get a bunch of output that looks like

cc -DNDEBUG -g -fwrapv -Os .....
.....
cc -DNDEBUG -g -fwrapv -Os .....
.....

And at the end it says:

ld: library not found for -lssl

clang: error: linker command failed with exit code 1 (use -v to see invocation)

error: command 'cc' failed with exit status 1

----------------------------------------
Cleaning up...
Command /usr/bin/python -c "import setuptools, tokenize;__file__='/private/var/folders/bz/pvj1g9xj16d10pjjgbrfl3fw0000gn/T/pip_build_root/psycopg2/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /var/folders/bz/pvj1g9xj16d10pjjgbrfl3fw0000gn/T/pip-uE3thn-record/install-record.txt --single-version-externally-managed --compile failed with error code 1 in /private/var/folders/bz/pvj1g9xj16d10pjjgbrfl3fw0000gn/T/pip_build_root/psycopg2
Storing debug log for failure in /Users/Tyler/Library/Logs/pip.log

---

Running easy_install or doing it from source both give me the same error at the end (the part about library not found for -lssl).

---

Running brew install (or upgrade) openssl yields the below

$ brew upgrade openssl
Error: openssl-1.0.1h already installed

Can anyone help me out?

回答1:

For anyone looking for a solution for this on macOS Sierra 10.12: I fixed this by installing the command line tools:

xcode-select --install

After that, pip install psycopg2 should work.

If it doesn't, you could also try to link against brew's openssl:

env LDFLAGS="-I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib" pip install psycopg2

with openssl installed via brew. Note that the brew link openssl --force does not work anymore:

$ brew link openssl --force                                                                                 17.5s
Warning: Refusing to link: openssl
Linking keg-only openssl means you may end up linking against the insecure,
deprecated system OpenSSL while using the headers from Homebrew's openssl.
Instead, pass the full include/library paths to your compiler e.g.:
  -I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib

As @macho points out below if this still does not work, you might need to use the --no-cache option of pip, e.g.

env LDFLAGS="-I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib" pip --no-cache install psycopg2

回答2:

When running brew link openssl I get the following message:

$ brew link openssl
Warning: Refusing to link: openssl
Linking keg-only openssl means you may end up linking against the insecure,
deprecated system OpenSSL while using the headers from Homebrew's openssl.
Instead, pass the full include/library paths to your compiler e.g.:
  -I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib

Following this advice here's the pip command you need to use:

$ pip install -r requirements.txt --global-option=build_ext --global-option="-I/usr/local/opt/openssl/include" --global-option="-L/usr/local/opt/openssl/lib"

回答3:

I've managed to fix it by using:

brew unlink openssl && brew link openssl --force

I am not sure how this differs from the brew uninstall/upgrades that I did on OpenSSL in prior attempts I've made. My assumption is that these operations left some of the "faulty" shared libraries which were preventing this from working. Note that this also fixed issues with installing python cryptography module.