Code:
jms@osc-franzibald:~$ pdfjoin --help
This is pdfjoin version 1.20
Usage: pdfjoin args
where args must include source pdf filenames and optionally also
* a LaTeX papersize, for example --paper a4paper
--paper letterpaper
* the output page orientation, one of --orient landscape
--orient portrait
* one of --fitpaper true
--fitpaper false
to specify whether output page sizes and orientations should match
those of the input pages. Use of --fitpaper true overrides --orient.
* a page-trimming specification such as
--trim "1cm 1cm 1cm 1cm"
(Note that trimming does not mix well with --frame true.)
* an "offset" specification such as
--offset "1cm 0.5cm"
to offset the position of output pages (see the pdfpages manual)
* one of --turn true
--turn false
according to whether or not landscape pages should be displayed in
landscape orientation
* one of --noautoscale true
--noautoscale false
for scaling of logical pages to fit (or not)
* a specific name for the output file, e.g. --outfile mybigfile.pdf
* one of --tidy true
--tidy false
according to whether or not temporary files should be deleted immediately.
If --tidy false is used, such files are left in /var/tmp.
Default arguments for you at this site are
--paper a4paper --trim "0 0 0 0" --offset "0 0" --turn true --noautoscale false --tidy true
For information and version history see http://www.warwick.ac.uk/go/pdfjam