Using existing healpix installation in a non-writable directory

[msyriac]

The instructions for using an existing healpix installation ask us to symbolically link the healpix lib and include directories into _deps. However, it seems that these directories are required to be writable, which may not be the case if healpix is made available as a system module on an HPC system.

After:

mkdir _deps
cd _deps
ln -s /cephfs/soukdata/software/healpix/3.83/include include
ln -s /cephfs/soukdata/software/healpix/3.83/lib lib

The specific error I get during pip installation from source is:

      /usr/bin/install: cannot create regular file '/shared_home/msyriac/repos/NaMaster/_deps/lib/libnmt.so.0.0.0': Permission denied

The full traceback is here:
https://pastebin.com/5mQMVNcT