doc: mention caveats with using install --compare

* doc/coreutils.texi (install invocation): Mention that install(1) may
not correctly determine the default user or permissions for installed
files, and so is best used with options specifying these attributes.

diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 8e4bacfb74251e6e30824571bc3be1e8216c59b6..92917f17fa75a142feeef49f4f5234e2b2c32e76 100644 (file)
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -8920,6 +8920,12 @@ The program accepts the following options.  Also see @ref{Common options}.
 Compare each pair of source and destination files, and if the destination has
 identical content and any specified owner, group, permissions, and possibly
 SELinux context, then do not modify the destination at all.
+Note this option is best used in conjunction with @option{--user},
+@option{--group} and @option{--mode} options, lest @command{install}
+incorrectly determines the default attributes that installed files would have
+(as it doesn't consider setgid directories and POSIX default ACLs for example).
+This could result in redundant copies or attributes that are not reset to the
+correct defaults.
 
 @item -c
 @opindex -c