Switch -AS - synchronize archive contents
If this switch is used when archiving, those archived files which are not present in the list of the currently added files, will be deleted from the archive. It is convenient to use this switch in combination with -u to synchronize contents of archive and archiving folder.
For example, after the command:
WinRAR a -u -as backup sources\*.cpp
the archive backup.rar will contain only *.cpp files from folder sources, all other files will be deleted from the archive. It looks similar to creating a new archive, but with one important exception: if no files are modified since the last backup, the operation is performed much faster than the creation of a new archive.