out the disk usage of directories, such as @file{/usr/tmp}, which
are often symbolic links.
+@itemx --files0-from=@var{FILE0}
+@opindex --files0-from=@var{FILE0}
+@cindex including files from @command{du}
+Rather than processing files named on the command line, process those
+in the NUL-separated list in file @var{FILE0}.
+This is useful with the @option{--summarize} (@option{-s}) option when
+the list of file names is so long that it may exceed a command line
+length limitation.
+In such cases, running @command{du} via @command{xargs} is undesirable
+because it splits the list into pieces and makes @command{du} print a
+total for each sublist rather than for the entire list.
+One way to produce a list of NUL-separated file names is with @sc{gnu}
+@command{find}, using its @option{-print0} predicate.
+Do not specify any @var{FILE} on the command line when using this option.
+
@optHumanReadable
@item -H
operand should not be a parenthesis or any of @command{expr}'s
operators like @code{+}, so you cannot safely pass an arbitrary string
@code{$str} to expr merely by quoting it to the shell. One way to
-work around this is to use the @command{GNU} extension @code{+},
+work around this is to use the @sc{gnu} extension @code{+},
(e.g., @code{+ "$str" = foo}); a more portable way is to use
@code{@w{" $str"}} and to adjust the rest of the expression to take
the leading space into account (e.g., @code{@w{" $str" = " foo"}}).