Combining ps files and pdf files

•  Ps files

To merge the files `slide1.ps', `slide2.ps', and `slide3.ps' into a new PostScript file, `slideshow.ps', type:

$ psmerge -oslideshow.ps slide1.ps slide2.ps slide3.ps

to install psmerge, in ubuntu type:

 $ sudo apt-get install psutils

• Pdf files 

First of all you will need the program called pdftk. You can get it by opening terminal and typing:

$ sudo apt-get install pdftk

Now you can merge pdf files by putting them in the same directory and typing:

$ pdftk 1.pdf 2.pdf 3.pdf cat output merged.pdf

or if you wish to merge files in alphabetical order you can simply type:

$ pdftk *.pdf cat output merged.pdf