<?xml version='1.0'?>
-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
SPDX-License-Identifier: LGPL-2.1+
<varlistentry>
<term><varname>C</varname></term>
<listitem><para>Recursively copy a file or directory, if the
- destination files or directories do not exist yet. Note that
- this command will not descend into subdirectories if the
- destination directory already exists. Instead, the entire
- copy operation is skipped. If the argument is omitted, files
- from the source directory
+ destination files or directories do not exist yet or the
+ destination directory is empty. Note that this command will not
+ descend into subdirectories if the destination directory already
+ exists and is not empty. Instead, the entire copy operation is
+ skipped. If the argument is omitted, files from the source directory
<filename>/usr/share/factory/</filename> with the same name
are copied. Does not follow symlinks.</para></listitem>
</varlistentry>
</varlistentry>
</variablelist>
- <para>If the exclamation mark is used, this line is only safe of
+ <para>If the exclamation mark is used, this line is only safe to
execute during boot, and can break a running system. Lines
without the exclamation mark are presumed to be safe to execute
at any time, e.g. on package upgrades.
(ctime). Any of these three (or two) values will prevent cleanup
if it is more recent than the current time minus the age
field.</para>
+
+ <para>Note that while the aging algorithm is run a 'shared' BSD file lock (see <citerefentry
+ project='man-pages'><refentrytitle>flock</refentrytitle><manvolnum>2</manvolnum></citerefentry>) is
+ taken on each directory the algorithm descends into (and each directory below that, and so on). If the
+ aging algorithm finds a lock is already taken on some directory, it (and everything below it) is
+ skipped. Applications may use this to temporarily exclude certain directory subtrees from the aging
+ algorithm: the applications can take a BSD file lock themselves, and as long as they keep it aging of
+ the directory and everything below it is disabled.</para>
</refsect2>
<refsect2>