When printing out postage labels for eBay sales, I wanted to make an A4 sized landscape print out, as opposed to the A5 sized default. I could usually switch to Windows and use my Acrobat Pro to do this, but wanted a linux way! Enter pdfcrop.
PDFCrop is a part of texlive-extra-utils, so it does drag a lot of dependencies and other stuff with it on install, but it is worth it.
sudo apt-get install texlive-extra-utils
Usage: default behaviour without any parameters is to crop away all the white space around the text or images on the pdf
If you want some margin around the content then for left,top,right,bottom do something like this:
pdfcrop --margins '10 10 10 10' input.pdf output.pdf
To crop into the content use negative values
pdfcrop --margins '-10 -10 -10 -10' input.pdf output.pdf
Will only crop a single pdf file, but you can script to crop multiple files