split postscript files for printing booklets

[Zhang Weiwu]

Hi. First I am completely newbie to both this group and postscript. I
just think maybe here I can find answer to my problem.

I used to print booklet with psbook + psnup. Simple. The new problem I
have is our designer can only produce postscript documents with 2 pages
tied into one. Suppose she produce a 4-page only booklet, it look like this:

 her PS file's page 1      her PS file's page 2

+----------+----------+  +----------+----------+
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|   -1-    |   -2-    |  |   -3-    |   -4-    |
+----------+----------+  +----------+----------+

 her PS file's page 3      her PS file's page 4

+----------+----------+  +----------+----------+
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|   -5-    |   -6-    |  |   -7-    |   -8-    |
+----------+----------+  +----------+----------+

While I need to print it like this:

  my PS file's page 1       my PS file's page 2

+----------+----------+  +----------+----------+
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|   -8-    |   -1-    |  |   -2-    |   -7-    |
+----------+----------+  +----------+----------+

 her PS file's page 3      her PS file's page 4

+----------+----------+  +----------+----------+
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|          |          |  |          |          |
|   -3-    |   -6-    |  |   -4-    |   -5-    |
+----------+----------+  +----------+----------+

The difficulty here is I have to split her PS file into two halves
before I can pipe it to psbook to generate new page layout.

So basically my question is: how to make a postscript file from original
file, with the page number doubled and each page in original file was
spitted vertically into two separate pages?

Thank very much in advance!