Testing shell_exec:
whoami: nobody

pwd: /var/www/html


Testing postgres access:
Command: sudo -u postgres psql bluebirds_ai -t -A -F'|' -c "SELECT COUNT(*) FROM blog_posts;" 2>&1
Result: '
We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:

    #1) Respect the privacy of others.
    #2) Think before you type.
    #3) With great power comes great responsibility.

sudo: a terminal is required to read the password; either use the -S option to read from standard input or configure an askpass helper
sudo: a password is required
'

Testing simpler query:
Command: sudo -u postgres psql bluebirds_ai -t -c "SELECT 'test';" 2>&1
Result: '
We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:

    #1) Respect the privacy of others.
    #2) Think before you type.
    #3) With great power comes great responsibility.

sudo: a terminal is required to read the password; either use the -S option to read from standard input or configure an askpass helper
sudo: a password is required
'