Rsync via PHP exec() with SSH passwordless ssh login

Question

If I run the command via php exec(): It does not work. But if I use bash, it runs perfect. Any idea what the problem might be.? I was thinking maybe it is executing rsync as

Answer 1

store the command in a shell script, since it has no dynamic parts, and then use exec() to execute the shell script.

# on command line    
echo 'rsync -au /var/www/html/f1/ user@000.000.000.000:/var/www/html/f2/' > sync_files

# On command line
chmod +x sync_files