2 Ghostscript

Ghostscript is useful tool to manipulate PDFs, PostScript, and other file formats. Ghostscript needs to be installed in your system before using it. To check whether it is installed, issue this command from a Terminal

gs --version

There are several ways to install it (e.g., brew, from https://www.ghostscript.com/index.html, etc.) in case you need it.

2.1 Bounding box

Find the bounding box of a ps/pdf file

gs -sDEVICE=bbox -dNOPAUSE -dBATCH  file

##Convert a batch of PDF to PS files

for f in *.pdf;
   gs -sDEVICE=ps2write -dNOPAUSE -dBATCH -sOutputFile=./psFigures/$f.ps $f;

2.2 Convert a batch of PDFs into JPGs

for i in *.pdf;
   gs -dQUIET -dBATCH -dNOPAUSE -sDEVICE=jpeg -r144
      -sOutputFile=./converted/$(basename $i .pdf).jpg $i;

2.3 Merge and compress PDFs in a directory

gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -dPDFSETTINGS=/prepress -sOutputFile=out.pdf *.pdf

2.4 Make a smaller file (in kB)

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dNOPAUSE -dQUIET -dBATCH
   -sOutputFile=compressed.pdf input.pdf

Make the pdf even smaller at 150 DPI:

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dNOPAUSE -dQUIET -dBATCH -dPDFSETTINGS=/ebook
   -sOutputFile=compressed.pdf  input.pdf