PDF manipulation

Combine images into a PDF file

Fist install ImageMagick ( pacman -S imagemagick on Arch Linux )

$ convert image1.jpg image2.jpg image3.jpg out.pdf

Fist install the ghostscript utility ( pacman -S ghostscript on Arch Linux )

$ gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/printer -dNOPAUSE -dQUIET -dBATCH -sOutputFile=out.pdf in.pdf

Note: The compression factor can be adjusted with the -dPDFSETTINGS parameter like this:

/screen selects low-resolution output similar to the Acrobat Distiller "Screen Optimized" setting.
/ebook selects medium-resolution output similar to the Acrobat Distiller "eBook" setting.
/printer selects output similar to the Acrobat Distiller "Print Optimized" setting.
/prepress selects output similar to Acrobat Distiller "Prepress Optimized" setting.
/default selects output intended to be useful across a wide variety of uses, possibly at the expense of a larger output file.

Fist install qpdf ( pacman -S qpdf on Arch Linux )

$ qpdf --password=pdf_password --decrypt password-protected.pdf out.pdf 
$ qpdf --encrypt user_password pdf_password key_length -- in.pdf out.pdf

Fist install qpdf ( pacman -S qpdf on Arch Linux )

$ qpdf --empty --pages in.pdf first-last -- out.pdf

Fist install qpdf ( pacman -S qpdf on Arch Linux )

$ qpdf --empty --pages first.pdf second.pdf third.pdf -- out.pdf