The following two steps will help you to compress PDFs in Linux using Ghostscript:
Install Ghostscript
Update your package lists:
sudo apt-get update
Install Ghostscript:
sudo apt-get install ghostscript
Compress PDF file
Compress your PDF file using the following command:
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dBATCH -dQUIET -sOutputFile=compressed_file.pdf original_file.pdf
In case you want to adjust the compression level (quality) change the -dPDFSETTINGS option using one of the following:
Low quality:
/screen
Moderate quality:
/ebook
Good quality:
/printer
Best quality:
/prepress
Few stats
Original file size: ~11.5 MB
Compression at moderate quality (/ebook): ~8 MB
Compression at low quality (/screen): ~2.2 MB