Describe how to tar gz a folder

Guides/shell.md

@@ -9,3 +9,9 @@ ln -s -T ~/Software/GitAhead/GitAhead ~/.bin/gitahead
 ```
 
 To use a physical link instead of a symlink, use `-S` instead of `-s`
+
+## Compress
+
+```sh
+sudo tar --create --gzip --file bck_var_log.tgz --verbose /var/log
+```