diff --git a/README.md b/README.md
index db5b175..6f82761 100644
--- a/README.md
+++ b/README.md
@@ -379,6 +379,8 @@ A few examples of piecing together commands:
 
 - `split `and `csplit`: splitting files
 
+- `sponge`: read all input to memory before wriring it, useful for reading from then writing to the same file (for example, `grep -v something some-file | sponge some-file`)
+
 - `units`: unit conversions and calculations; converts furlongs per fortnight to twips per blink (see also `/usr/share/units/definitions.units`)
 
 - `7z`: high-ratio file compression