rsync: How to Use in a PHP File

I’m trying to send an image file from one server to another using rsync. The sending server’s public key has been placed into the receiving server’s /root/.ssh/authorized_keys . (I’ll not use root later on. Just trying to keep things as simple as possible for now.)

I can get an image copied successfully to the receiving server from the command line.

rsync -va /var/www/html/nameofimage.jpg root@111.222.333.444:/images/

However, I do not know how to write this into a PHP file. I thought this would work.

<?php 
exec('rsync -va /var/www/html/nameofimage.jpg root@111.222.333.444:/images/');
?>

But when this file is invoked from the command line, I receive the message … rsync: link_stat “/home/myusername/ssh” failed: No such file or directory (2) rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1183) [sender=3.1.0]

Thanks for any direction with this.