问题
After the installation of opam, it asks to do eval `opam config env`.
What is the exact usage of it?
回答1:
It will setup environment variables, that are necessary for the toolchain to work properly, e.g., CAML_LD_LIBRARY_PATH.
It is like activating virtual environment in Python's virtualenv.
If you want to see what variables are set exactly, the you can run it without the eval part:
$ opam config env
CAML_LD_LIBRARY_PATH="/home/ivg/.opam/4.02.1/lib/stublibs"; export CAML_LD_LIBRARY_PATH;
MANPATH=":/home/ivg/.opam/4.02.1/man"; export MANPATH;
PERL5LIB="/home/ivg/.opam/4.02.1/lib/perl5:"; export PERL5LIB;
OCAML_TOPLEVEL_PATH="/home/ivg/.opam/4.02.1/lib/toplevel"; export OCAML_TOPLEVEL_PATH;
PATH="/home/ivg/.opam/4.02.1/bin:/home/ivg/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games"; export PATH;
来源：https://stackoverflow.com/questions/30155960/what-is-the-use-of-eval-opam-config-env