Compressing PDFs with a Simple CLI Command

Have you ever needed to compress a PDF but didn’t want to use bulky software or online tools? Today, I learned about a neat way to do it using Ghostscript, a powerful command-line tool.

Why Use This?

• No online tools needed: Perfect for privacy-conscious users.
• Customizable: You can choose the compression level based on your needs.
• Lightweight and fast: Ghostscript is highly efficient.

Main command

Here’s the command in action:

compresspdf() {
	gs -sDEVICE=pdfwrite -dNOPAUSE -dQUIET -dBATCH -dPDFSETTINGS=/${3:-"screen"} -dCompatibilityLevel=1.4 -sOutputFile="$2" "$1"
}

This little shell function, named compresspdf, takes three arguments:

• Input file: The PDF you want to compress.
• Output file: The compressed version of the PDF.
• Compression level: An optional setting to control the quality of the output.

How It Works

The function uses Ghostscript (gs), a versatile tool for processing PDFs and PostScript files, with the following options:

• -sDEVICE=pdfwrite: Specifies the output as a PDF.
• -dPDFSETTINGS: Determines the compression level. Options include:
  • screen (default): Low resolution for online viewing.
  • ebook: Medium resolution for eBooks.
  • printer: High resolution for printing.
  • prepress: Maximum quality for professional printing.
• -dCompatibilityLevel=1.4: Ensures the PDF is compatible with older readers.
• -sOutputFile: Specifies the output file.

Bash script

Create a bash script file compresspdf.sh with bellow content

#!/bin/bash

# Usage: compresspdf [input file] [output file] [screen*|ebook|printer|prepress]

# Check that the required arguments are provided
if [ $# -lt 2 ]; then
    echo "Usage: compresspdf [input file] [output file] [screen*|ebook|printer|prepress]"
    exit 1
fi

compresspdf() {
    gs -sDEVICE=pdfwrite -dNOPAUSE -dQUIET -dBATCH -dPDFSETTINGS=/${3:-"ebook"} -dCompatibilityLevel=1.4 -sOutputFile="$2" "$1"
}

compresspdf "$1" "$2" "$3"

Make it executable

 chmod +x ./compresspdf.sh

Usage

Here’s how to use the function:

Run it with the required arguments:

./compresspdf.sh input.pdf output.pdf [compression_level]

For example:

./compresspdf.sh ./input.pdf ./output.pdf ebook

If you don’t specify a compression level, it defaults to screen, which is optimized for smaller file sizes.

Takeaway

This function is a handy addition to any developer’s toolkit, saving time and effort while maintaining full control over PDF compression.

Do you use a similar tool or script for handling PDFs? Let me know in the comments!