/cr Find the size of HKEY_CLASSES_ROOT
/cu Find the size of HKEY_CURRENT_USER
/u Find the size of HKEY_USERS
/lm Find the size of HKEY_LOCAL_MACHINE
/a All. Find the size of entire registry.
</Subtree switch> "registry path" Find the size of any registry key
e.g. dureg /lm "software\microsoft" finds the size of the HKLM\Software\Microsoft key
/s "string" Search for string in the registry
e.g. dureg /s "video" finds all occurrences of "video" in the registry
/s [/subtree switch] "string" Search for string in the registry subtree
e.g. dureg /lm /s "video" finds all occurrences of "video" in the HKLM
(to stop a search, press Ctrl+Break)