diff --git a/blog - fun with find.md b/blog - fun with find.md
index 91771ff..f41c39f 100644
--- a/blog - fun with find.md	
+++ b/blog - fun with find.md	
@@ -1,47 +1,62 @@
-# Fun with Find
-
-## Find the total size of certain files within a directory branch
-
-```bash
-find <path> -type f -iname '*-bin*' -exec du -ch {} +
-```
-
----
-
-## Find files larger than...  
-
-
-### 100M:  
-
-
-```bash
-find . -type f -size +100000k -exec ls -lh {} \; | awk '{ print $9 ": " $5 }'
-```
-
-### 1G:  
-
-
-```bash
-find . -type f -size +1000000k -exec ls -lh {} \; | awk '{ print $9 ": " $5 }'
-```
-
-...and so on...
-
----
-
-## Find, archive and purge old files
-
-```bash
-# Find disk space used by logfiles older that 360 days
-find /var/log/hbase -type f -iname "*log*" -mtime +360 -exec du -ch {} +
-
-# Archive those files to another location
-find /var/log/hbase -type f -iname "*log*" -mtime +360 -print0 | xargs -0 tar cfz /tmp/hbase-logs.tgz
-
-# Delete the original files
-find /var/log/hbase -type f -iname "*log*" -mtime +360 -delete
-```
-
-Replace `hbase` with the log directory you want to search.  If you don't need to save the archives anywhere, skip step two.
-
-[Reference](https://www.cyberciti.biz/faq/linux-unix-find-tar-files-into-tarball-command/)
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+# Fun with Find
+
+## Find the total size of certain files within a directory branch
+
+```bash
+find <path> -type f -iname '*-bin*' -exec du -ch {} +
+```
+
+---
+
+## Find files larger than...  
+
+
+### 100M:  
+
+
+```bash
+find . -type f -size +100000k -exec ls -lh {} \; | awk '{ print $9 ": " $5 }'
+```
+
+### 1G:  
+
+
+```bash
+find . -type f -size +1000000k -exec ls -lh {} \; | awk '{ print $9 ": " $5 }'
+```
+
+...and so on...
+
+---
+
+## Find, archive and purge old files
+
+```bash
+# Find disk space used by logfiles older that 360 days
+find /var/log/hbase -type f -iname "*log*" -mtime +360 -exec du -ch {} +
+
+# Archive those files to another location
+find /var/log/hbase -type f -iname "*log*" -mtime +360 -print0 | xargs -0 tar cfz /tmp/hbase-logs.tgz
+
+# Delete the original files
+find /var/log/hbase -type f -iname "*log*" -mtime +360 -delete
+```
+
+Replace `hbase` with the log directory you want to search.  If you don't need to save the archives anywhere, skip step two.
+
+[Reference](https://www.cyberciti.biz/faq/linux-unix-find-tar-files-into-tarball-command/)
+
+---
+
+## Find files by group and mode
+
+Note: *from Teachingbooks web directory permission fix.* at OverDrive
+
+Find files that have `group: www-data` and current `permissions: 644`, then update the permissions to 664
+
+```bash
+find <directory> -type f -group www-data -perm 644 -exec ls -al {} \;
+find <directory> -type f -group www-data -perm 644 -exec chmod g+w {} \;
+```
+
+[Reference](https://ostechnix.com/find-files-based-permissions/)
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