compsize: add page (#5685)

pages/linux/compsize.md

@@ -0,0 +1,17 @@
+# compsize
+
+> Calculate the compression ratio of a set of files on a btrfs filesystem.
+> See also `btrfs filesystem` for recompressing a file by defragmenting it.
+> More information: <https://github.com/kilobyte/compsize>.
+
+- Calculate the current compression ratio for a file or directory:
+
+`sudo compsize {{path/to/file_or_directory}}`
+
+- Don't traverse filesystem boundaries:
+
+`sudo compsize --one-file-system {{path/to/file_or_directory}}`
+
+- Show raw byte counts instead of human-readable sizes:
+
+`sudo compsize --bytes {{path/to/file_or_directory}}`