dirname: add page (#2251)

pages/linux/dirname.md

@@ -0,0 +1,15 @@
+# dirname
+
+> Calculates the parent directory of a given file or directory path.
+
+- Calculate the parent directory of a given path:
+
+`dirname {{path/to/file_or_directory}}`
+
+- Calculate the parent directory of multiple paths:
+
+`dirname {{path/to/file_a}} {{path/to/directory_b}}`
+
+- Delimit output with a NUL character instead of a newline (useful when combining with `xargs`):
+
+`dirname --zero {{path/to/directory_a}} {{path/to/file_b}}`