Add csplit file-write

Co-authored-by: Andrea Cardaci <cyrus.and@gmail.com>

_gtfobins/csplit.md

@@ -5,6 +5,13 @@ functions:
         LFILE=file_to_read
         csplit $LFILE 1
         cat xx01
+  file-write:
+    - description: Writes the data to `xx0file_to_write`. If needed, a different prefix can be specified with `-f` (instead of `xx`).
+      code: |
+        TF=$(mktemp)
+        echo "DATA" > $TF
+        LFILE=file_to_write
+        csplit -z -b "%d$LFILE" $TF 1
   suid:
     - code: |
         LFILE=file_to_read