Set NVM_DIR to real path to avoid symlink issues in #617

[singlow]

Proposed solution for #617

This pull request modifies NVM_DIR early in nvm.sh to point to the actual target of the symlink if the path is a symlink.

This way we don't have to worry about nvm actually working on a symlinked path. Is there a downside to this?

I commented a solution I am using on #855, but it used readlink which is non-Posix. The following is the alternative using pwd -P in the same way that this pull request does.

export NVM_DIR=$(cd ~/.nvm && pwd -P)
[ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh"  # This loads nvm

[ljharb]

This would need tests to ensure it works across shell versions.

[btelles]

@singlow , Any chance you'd be willing to write a test for this? Sure would help reduce clutter in our environment. :-P

[ljharb]

I'll also want benchmarks to show how much this slows down shell startup time, in zsh and bash specifically (since zsh has the hardest time being fast with nvm).

[singlow]

I will work on that ASAP

[ljharb]

@singlow do you have any interest in completing this PR?

[ljharb]

ping @singlow; even if you're not interested in completing the PR, could you check the "allow edits" box on the RHS of the PR?