Improve documentation.

* doc/tar.1: Document --skip-old-files and --warning=existing-file
* doc/tar.texi: Document --warning=existing-file

doc/tar.1

@@ -13,7 +13,7 @@
 .\"
 .\" You should have received a copy of the GNU General Public License
 .\" along with this program.  If not, see <http://www.gnu.org/licenses/>.
-.TH TAR 1 "February 22, 2014" "TAR" "GNU TAR Manual"
+.TH TAR 1 "August 16, 2014" "TAR" "GNU TAR Manual"
 .SH NAME
 tar \- an archiving utility
 .SH SYNOPSIS
@@ -347,6 +347,9 @@ Recursively remove all files in the directory prior to extracting it.
 \fB\-\-remove\-files\fR
 Remove files from disk after adding them to the archive.
 .TP
+\fB\-\-skip\-old\-files
+Don't replace existing files when extracting, silently skip over them.
+.TP
 \fB\-U\fR, \fB\-\-unlink\-first\fR
 Remove each file prior to extracting over it.
 .TP
@@ -1021,6 +1024,9 @@ Keywords applicable for \fBtar --create\fR:
 .HP
 Keywords applicable for \fBtar --extract\fR:
 .TP
+.B existing\-file
+"%s: skipping existing file"
+.TP
 .B timestamp
 "%s: implausibly old time stamp %s"
 .br

doc/tar.texi

@@ -4316,6 +4316,10 @@ Disable all warning messages.
 
 @subheading Keywords applicable for @command{tar --extract}
 @table @asis
+@kwindex existing-file
+@cindex @samp{%s: skipping existing file}, warning message
+@item existing-file
+@samp{%s: skipping existing file}
 @kwindex timestamp
 @cindex @samp{implausibly old time stamp %s}, warning message
 @cindex @samp{time stamp %s is %s s in the future}, warning message