bin/srsync-incremental: Add, incremental backups with rsync.

diff --git a/bin/srsync-incremental b/bin/srsync-incremental
new file mode 100755 (executable)
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+++ b/bin/srsync-incremental
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+#!/bin/sh
+
+# Perform incremental backups using rsync and hardlinks.
+#
+# Thanks to http://www.sanitarium.net/golug/rsync_backups_2010.html for the
+# idea.
+
+# Copyright (C) 2011-2012  Simon Ruderich
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+if [ $# -lt 2 ]; then
+    echo "Usage: $0 <backups-directory> <arguments to rsync>" >&2
+    echo
+    echo "Note: The target directory is the _first_ argument!" >&2
+    exit 2
+fi
+
+cd "$1" || exit 1
+shift
+
+dest=`echo backup-*`
+if [ "x$dest" != 'xbackup-*' ]; then
+    dest="`pwd`/`ls -1d backup-* | tail -n1`"
+fi
+
+target=backup-`date '+%Y-%m-%d-%H-%M-%S'`
+
+if [ -d current ]; then
+    echo "Target directory 'current' already exists, aborting." >&2
+    exit 1
+fi
+
+mkdir current
+rsync \
+    --verbose --human-readable \
+    --archive --hard-links --numeric-ids --one-file-system \
+    --link-dest="$dest" \
+    "$@" current \
+&& mv current "$target"