This is a really cool feature of the Egroupware filemanager. When you are running Egroupware on a system where you want to access the files of a particular system user, you can mount the real filesystem in the Egroupware filemanager. On a command line type:
{path to Egroupware filemanager/cli.php} mount ‘filesystem://root_{username of Egroupware header manager}:{password of Egroupware header manager}@default{directory on real filesystem}?user={Egroupware username}’ {path in Egroupware filemanager}
E.g. on a Linux system with a Egroupware header manager named admin and a password set to adminpassword, a system user named raging and a Egroupware user named goblin, the following command will mount a (read-only) directory in the filesystem under /home/goblin/raging:
/srv/www/htdocs/egroupware/filemanager/cli.php mount ‘filesystem://root_admin:adminpassword@default/home/raging?user=goblin’ /home/raging/raging
See this thread for more info about it.