Fix 'pv' filename

lurch · lurch · commit 38e8b097fea9 · 2015-03-21T18:21:56.000Z
so that it uses the same filename as the 'cat' example
diff --git a/linux/filesystem/backup.md b/linux/filesystem/backup.md
@@ -39,7 +39,7 @@ cat recipes.sql | mysql recipes
 Alternatively, you can use the `pv` command (not installed by default, so install with `apt-get install pv`) to see a progress meter as the dumpfile is processed by MySQL. This is useful for large files:
 
 ```
-pv recipes | mysql recipes
+pv recipes.sql | mysql recipes
 ```
 
 ## SD card image
