Running PhantomJS through exec() - issue with including ~/.fonts - php

Question

I am able to run PhantomJS from both the shell and exec() fine. The server I am using looks for additional fonts in the ~/.fonts/ directory. When those additional fonts are present, from the shell only I am able to take a screenshot with PhantomJS and the expected fonts render well.
> strace ~/public_html/api/libraries/phantomjs-2.1.1-linux-x86_64/bin/phantomjs ~/public_html/api/libraries/phantomjs-2.1.1-linux-x86_64/examples/rasterize.js http://v1.jontangerine.com/silo/typography/web-fonts/ ~/tmp/test.jpg | grep font
open("/home/user1/.fonts/TTF/verdana.ttf", O_RDONLY) = 11
open("/home/user1/.fonts/TTF/AndaleMo.TTF", O_RDONLY) = 11
open("/home/user1/.fonts/TTF/arial.ttf", O_RDONLY) = 11
open("/home/user1/.fonts/TTF/cour.ttf", O_RDONLY) = 11
open("/home/user1/.fonts/TTF/georgia.ttf", O_RDONLY) = 11
open("/home/user1/.fonts/TTF/impact.ttf", O_RDONLY) = 11
...
When I try the same command from from exec(), the user fonts directory is not searched.
<?php
exec('strace ~/public_html/api/libraries/phantomjs-2.1.1-linux-x86_64/bin/phantomjs ~/public_html/api/libraries/phantomjs-2.1.1-linux-x86_64/examples/rasterize.js http://v1.jontangerine.com/silo/typography/web-fonts/ ~/tmp/test.jpg | grep font');
The ~/.fonts directory is not searched, but a screenshot is written to disk without the proper fonts being rendered.
I understand exec() to run as the Apache user so user fonts won't be used. However,
> whoami
user1
and
<?php
echo exec('whoami');
user1
both show as the same user, so I suspect this is misleading because this works perfectly (fonts and all) in the shell:
php -r "exec('~/public_html/api/libraries/phantomjs-2.1.1-linux-x86_64/bin/phantomjs ~/public_html/api/libraries/phantomjs-2.1.1-linux-x86_64/examples/rasterize.js http://v1.jontangerine.com/silo/typography/web-fonts/ ~/tmp/test.jpg');"
I understand setuid can allow users to exec a program with the permissions of its owner (user1), but this doesn't help. This particular server is a shared server, and su and sudo are disabled so running as a different user is not permitted.
Linux user configurations isn't my area of expertise, but using exec() how to run the PhantomJS command so the user fonts are included?
Research:
Running PhantomJS from PHP with exec() - the problem was with $PATH
PHP + PhantomJS Rasterize - This was a problem with HostGator
exec() and phantomjs issue with absolute paths - One answer suggested running the command as a cron which won't work. Also modifying /etc/sudoers is not possible.

Answer 1

The problem revealed itself when printenv and exec('printenv') were run, respectively
HOME=/home/user1
and
HOME=/home/user1/tmp
This means that even though whoami and exec('whoami') both return user1, something in the shared host configuration set the home directory to /tmp, which is wise to sandbox the script.
The solution is to prepend export HOME=~; (not HOME=~;) to the exec command. i.e.
exec('export HOME=~; strace ~/public_html/api/libraries/phantomjs-2.1.1-linux-x86_64/bin/phantomjs ~/public_html/api/libraries/phantomjs-2.1.1-linux-x86_64/examples/rasterize.js http://v1.jontangerine.com/silo/typography/web-fonts/ ~/tmp/test.jpg | grep font');
This will cause the HOME directory to be set and the user fonts can now be searched.