dmflags

 1141576772 dm1
286375424 dm2
0 dm3
ould it be possible to run the script in a separate screen?

sudo apt-get install screen

Then use screen -S screenname where screenname is a name you give the screen session.

Once in the screen, you can then enter your command, php buildscript/build_css.php

To leave the session, use ctrl+a+d.

To get back into the session, use screen -r screenname

Do not worry, when you leave the session, the command will stay running in the background.