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Linux-installer.md

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+This document explains how the
+[BOINC Linux installer](https://boinc.berkeley.edu/linux_install.php)
+works.
+
+## Users and groups
+
+The installer creates a user ```boinc```
+and a group ```boinc```.
+
+All files created by the installer are owned by ```boinc```,
+and all BOINC processes (the client and science applications)
+run under ```boinc```.
+This provides a measure of protection,
+since these processes cannot
+access file or directories with no 'other' permissions set.
+
+## Files
+
+## Execution