chuckhoupt · February 20, 2023 18:48 · Aug 19, 2013 · Aug 19, 2013 · Aug 19, 2013 · Aug 19, 2013
diff --git a/Read Me.md b/Read Me.md
@@ -24,8 +24,8 @@ truly duplicated. This is done by combining find's modification-time
 filter (-mtime) and cpio's pass-thru hard-link mode (-p and -l). The
 basic core of the script are the commands:
 
-  find $HOME -mtime -30d -print | cpio -dpl $SHADOW_HOME
-  rsync -avz --delete --omit-dir-times $SHODOW_HOME/ $BACKUP_ACCOUNT:recent-changes
+    find $HOME -mtime -30d -print | cpio -dpl $SHADOW_HOME
+    rsync -avz --delete --omit-dir-times $SHODOW_HOME/ $BACKUP_ACCOUNT:recent-changes
 
 Much of the script bulk is added filtering to eliminate temporary or
 derivative files and directories from the process.
diff --git a/Read Me.md b/Read Me.md
@@ -3,8 +3,8 @@ Backup-Recent Shell Script
 
 Offsite backups can be very useful for disaster recovery. However,
 backing up all data to the cloud can be slow and expensive. A compromise
-is to backup only recently modified data to the cloud. Many online
-services provide small amounts of online storage, which can be useful
+is to backup only recently modified data to the cloud. Many ISPs/WebHosts
+provide small amounts of online storage, which can be useful
 for recent-file backup. For example, DreamHost accounts come with 50GB
 of free backup storage -- not enough for a complete backup, but plenty
 of space to hold many months of recent work.

diff --git a/Read Me.md b/Read Me.md
@@ -1,3 +1,31 @@
-Backup-Recent.command
-=====================
+Backup-Recent Shell Script
+==========================
 
+Offsite backups can be very useful for disaster recovery. However,
+backing up all data to the cloud can be slow and expensive. A compromise
+is to backup only recently modified data to the cloud. Many online
+services provide small amounts of online storage, which can be useful
+for recent-file backup. For example, DreamHost accounts come with 50GB
+of free backup storage -- not enough for a complete backup, but plenty
+of space to hold many months of recent work.
+
+How it Works
+------------
+
+Although rsync is very powerful, it doesn't have an option to filter
+files based on age. To work around this, the script creates a scratch
+shadow copy of the user's home directory containing only recently
+modified files.
+
+Of course, a naive shadow copy of recent files would consume large
+amounts of disk and time. For efficiency, the shadow copy is built with
+hard-linked copies, which means only a partial directory structure is
+truly duplicated. This is done by combining find's modification-time
+filter (-mtime) and cpio's pass-thru hard-link mode (-p and -l). The
+basic core of the script are the commands:
+
+  find $HOME -mtime -30d -print | cpio -dpl $SHADOW_HOME
+  rsync -avz --delete --omit-dir-times $SHODOW_HOME/ $BACKUP_ACCOUNT:recent-changes
+
+Much of the script bulk is added filtering to eliminate temporary or
+derivative files and directories from the process.
diff --git a/backup-recent.sh → Backup-Recent.sh b/backup-recent.sh → Backup-Recent.sh
diff --git a/backup-recent.command → backup-recent.sh b/backup-recent.command → backup-recent.sh
diff --git a/Backup-Recent.command → backup-recent.command b/Backup-Recent.command → backup-recent.command
diff --git a/Backup-Recent.command b/Backup-Recent.command
@@ -0,0 +1,56 @@
+#!/bin/bash
+
+set -eux
+
+BACKUP_ACCOUNT=backupuser@backup.example.com
+
+MAXSIZE=45000000000
+
+# Wait for the net to come up
+while [ ! $(ifconfig | grep 'status: active') ]; do
+    sleep 1
+done 
+
+HOST=$(hostname -s)
+
+DAYS=180
+
+SHADOW_DIR=/tmp/$HOST-$USER-recent
+
+if true
+then
+rm -rf $SHADOW_DIR
+mkdir $SHADOW_DIR
+
+date
+
+find "$HOME" \
+-path "$HOME/Library" -prune -or \
+-path "$HOME/Pictures/iPhoto Library/Thumbnails" -prune -or \
+-path "$HOME/Music/iTunes" -prune -or \
+-path "$HOME/.Trash" -prune -or \
+-path "$HOME/.m2" -prune -or \
+-path "$HOME/Downloads" -prune -or \
+-name .svn -prune -or \
+-name CVS -prune -or \
+-name 'iPod Photo Cache' -prune -or \
+-not -type d \
+-not -name .DS_Store \
+-not -name '*.o' \
+-not -name '*.class' \
+-not -name '*.jar' \
+-mtime -$DAYS \
+-print \
+| cpio -pdl $SHADOW_DIR
+
+date
+
+du -sk $SHADOW_DIR
+
+fi
+
+# omit dir times, because cpio doesn't preserve dir times, causing re-sync every time
+rsync -avz --delete --stats --omit-dir-times \
+"$SHADOW_DIR"/ $BACKUP_ACCOUNT:"$HOST-$USER-recent"
+
+rm -rf $SHADOW_DIR
diff --git a/Read Me.md b/Read Me.md
@@ -0,0 +1,3 @@
+Backup-Recent.command
+=====================
+
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