extundelete: add page (#4327)

pages/linux/extundelete.md

@@ -0,0 +1,21 @@
+# extundelete
+
+> Recover deleted files from ext3 or ext4 partitions by parsing the journal.
+> See also `date` for Unix time information and `umount` for unmounting partitions.
+> More information: <http://extundelete.sourceforge.net>.
+
+- Restore all deleted files inside partition N on device X:
+
+`sudo extundelete {{/dev/sdXN}} --restore-all`
+
+- Restore a file from a path relative to root (Do not start the path with `/`):
+
+`extundelete {{/dev/sdXN}} --restore-file {{path/to/file}}`
+
+- Restore a directory from a path relative to root (Do not start the path with `/`):
+
+`extundelete {{/dev/sdXN}} --restore-directory {{path/to/directory}}`
+
+- Restore all files deleted after January 1st, 2020 (in Unix time):
+
+`extundelete {{/dev/sdXN}} --restore-all --after {{1577840400}}`