val wc_c : t -> string -> int
(** count characters in a file *)
+val head : t -> string -> string array
+(** return first 10 lines of a file *)
+
+val head_n : t -> int -> string -> string array
+(** return first N lines of a file *)
+
+val tail : t -> string -> string array
+(** return last 10 lines of a file *)
+
+val tail_n : t -> int -> string -> string array
+(** return last N lines of a file *)
+
+val df : t -> string
+(** report file system disk space usage *)
+
+val df_h : t -> string
+(** report file system disk space usage (human readable) *)
+
+val du : t -> string -> int64
+(** estimate file space usage *)
+