Add spell.sh example to Git filtering notes.

diff --git a/posts/Git/notes.org b/posts/Git/notes.org
index ab5a547567176eb7a9a7780f3e27313f07da0bc3..5c6da8c42dd07e83c9ad0803a21ba12f689878d3 100644 (file)
--- a/posts/Git/notes.org
+++ b/posts/Git/notes.org
@@ -498,7 +498,14 @@ Create a filtered version of =REPO_A=:
     : $ git filter-branch --prune-empty --index-filter "$SPELL" -- --all
 
 Alter the =grep= stuff as you need.  The goal is to remove anything
-you want to keep from the listing produced by =SPELL=.
+you want to keep from the listing produced by =SPELL=.  If the spell
+becomes too complicated, you can move it to a standalone script:
+
+    : $ cat /tmp/spell.sh
+    : #!/bin/bash
+    : git ls-tree -r …
+    : …
+    : $ git filter-branch --prune-empty --index-filter /tmp/spell.sh -- --all
 
 Merge it into =REPO_B=: