Update README.md

README.md

@@ -36,6 +36,14 @@ Some are 3000 pixels to a side. Some are 4000. Some are 6000 !
 
 Also they are a mix of .jpg, .jpeg, and .png
 
+# Tip on isolating images
+
+If you want to find all images with a particular thing tagged, for example, "dog",
+then in Linux, you can do something like
+
+find . -name '*.txt' | xargs grep -l dog >/tmp/dog.list
+
+
 # Acknowlegements
 Thank you to the good folks of Pexels.com who have put together a great free resource.
 It's still the best place to go if you want a nice human-friendly interface to browse and possibly download