How to find PDF page orientation with 'pdftk'?

I need to find PDF page orientations with pdftk.

I need to rotate landscape pages to portrait.

It will be good if I get to know to find page height and width so that I can rotate files.

Can I find this by using pdftk?
Or can I find this in the PDF source code?
Are there other methods to acquire this information?

Solution

First:

You cannot use pdftk to query PDF for its pages' orientation.
But you can use pdfinfo instead to find out which pages are landscape and which are portrait.
After you know, use pdftk to rotate that selection of pages which you want rotated into whichever direction you need.

Second: Understanding pdfinfo

Use -f N -l M to query for information about a certain page range, here pages N-M.
Use -box to get all the different *Box dimensions which may or may not be explicitely defined for the PDF pages: /MediaBox (MUST be present), /CropBox (optional), /ArtBox (optional), /TrimBox (optional) and /BleedBox (optional). (pdfinfo assumes and reports identical values to the /MediaBox for all optional boxes if they are not explicitely defined.)
Be aware that a /CropBox, if defined, limits the area of the complete page which is displayed in a PDF viewer or which is printed on paper. You can have a portrait A3 page (MediaBox) where the CropBox limits your view to a landscape-looking, A5-sized clipping only!
Be aware that an internal page /Rotation key inserted into the PDF source code may tell the viewer to display the page differently from how it is defined.

Third: Using pdfinfo

Here is an example for running pdfinfo against a real-world PDF which uses different page sizes, *boxes and rotations, extracting the page size details about the range 3-5:

$ pdfinfo -box -f 3 -l 5 sample.pdf
  Title:          sample.pdf
  Author:         SYSTEM
  Creator:        Adobe Acrobat 9.3.2
  Producer:       GPL Ghostscript 8.71
  CreationDate:   Sat Jun  5 00:55:42 2010
  ModDate:        Sat Jun  5 00:55:42 2010
  Tagged:         no
  UserProperties: no
  Suspects:       no
  Form:           none
  JavaScript:     no
  Pages:          8
  Encrypted:      no
  Page    3 size: 612 x 792 pts (letter)
  Page    3 rot:  90
  Page    4 size: 565 x 782 pts
  Page    4 rot:  0
  Page    5 size: 842 x 1191 pts (A3)
  Page    5 rot:  270
  Page    3 MediaBox:     0.00     0.00   612.00   792.00
  Page    3 CropBox:      0.00     0.00   612.00   792.00
  Page    3 BleedBox:     0.00     0.00   612.00   792.00
  Page    3 TrimBox:      0.00     0.00   612.00   792.00
  Page    3 ArtBox:       0.00     0.00   612.00   792.00
  Page    4 MediaBox:     0.00     0.00   595.00   842.00
  Page    4 CropBox:     10.00    20.00   575.00   802.00
  Page    4 BleedBox:    10.00    20.00   575.00   802.00
  Page    4 TrimBox:     10.00    20.00   575.00   802.00
  Page    4 ArtBox:      10.00    20.00   575.00   802.00
  Page    5 MediaBox:     0.00     0.00   842.00  1191.00
  Page    5 CropBox:      0.00     0.00   842.00  1191.00
  Page    5 BleedBox:     0.00     0.00   842.00  1191.00
  Page    5 TrimBox:      0.00     0.00   842.00  1191.00
  Page    5 ArtBox:       0.00     0.00   842.00  1191.00
  File size:      28947 bytes
  Optimized:      yes
  PDF version:    1.4

I recommend you to study above output very closely. Don't miss the lines which state the rot: (page rotation) angle. See also the possible differences in what is given as size: and what is given for MediaBox.