get user's home

[Joshua Root]

On 2017-8-5 06:46 , Umesh Singla wrote:
> On a side note, I didn't get this part:
> 
>     The user installing the port is not necessarily the one that will
>     use it.

Suppose a port is built on the buildbot. The user is 'buildbot' and so 
the value of $user_home will be something like '/Users/buildbot'. An end 
user then installs the port on their system. The value of $user_home 
will be different, for example '/Users/steve'. So if anything involving 
the value of $user_home ended up in the binary archive, it is wrong on 
the user's system.

- Josh