Rotate a PDF under Ubuntu Linux

Use the PDF toolkit Show archive.org snapshot :

Copysudo apt-get install pdftk

To rotate page 1 by 90 degrees clockwise:

Copypdftk in.pdf cat 1E output out.pdf    # old pdftk
pdftk in.pdf cat 1east output out.pdf # new pdftk

To rotate all pages clockwise:

Copypdftk in.pdf cat 1-endE output out.pdf    # old pdftk
pdftk in.pdf cat 1-endeast output out.pdf # new pdftk

The E (old pdftk) or east (new pdftk) is meaningful if you want other rotations. From the man page:

The page rotation setting can cause pdftk to rotate pages and documents.
Each option sets the page rotation as follows (in degrees): north: 0, east: 90, south: 180, west: 270, left: -90, right: +90, down: +180. left, right, and down make relative adjustments to a page's rotation.