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<concept id="GUID-57DD8365-E60F-55C6-BB24-8D215A31A8AF" xml:lang="en"><title>How
to track changes</title><shortdesc>This topic describes hoe to track changes made to file and free
disk space.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<section id="GUID-DF41D2BE-1FD6-421F-9D07-49CCAC7AC288"><title>File changes</title> <p>To be notified whenever there is a
change in the file system, use <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-5F5D51B6-2643-3482-8C9F-71DF6C3355C4"><apiname>RFs::NotifyChange()</apiname></xref>. This
is better than having to poll regularly. </p> <p>Use the <codeph>TOpenFileScan</codeph> class
to find out which files are open, and the thread id of the program that has
them open. This is useful for programs such as shells to be able to highlight
files that are presently open. It is also useful for backup programs, which
may need to close or suspend the owning program before doing a backup. </p> </section>
<section id="GUID-754E8C5D-BE23-43D7-93BB-9B22B89E4241"><title>Free disk space changes</title> <p>Clients can use <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-38A2D71A-DDB5-355D-863D-43802C67D51F"><apiname>RFs::NotifyDiskSpace()</apiname></xref> to
ask that they be notified when free disk space on a drive crosses a client
defined threshold value. This means that a client is notified if free disk
space either increases above the threshold value or decreases below that value. </p> </section>
</conbody></concept>