How to join two pdf files (in Linux):
yum install pdfjam
# pdfjoin file1.pdf file2.pdf
Where file1.pdf and file2.pdf are the pdf files to be joined.
output will be file2_joined.pdf
(So, You need not specify this output file as part of pdfjoin command)
How to rotate a pdf file and then save (in Linux):
rotate using menus. then just save the file. thats it :)