# Compressing PDF Files using MacOS or Linux

The method I’m using requires `ghostscript`. Ghostscript is a high quality, high performance Postscript and PDF interpreter and rendering engine.

If you’re using a Mac, you can install `ghostscript` using `brew`:

```
brew install ghostscript
```

If you’re using Linux you can install `ghostscript` from `aptitude`, or your package manager of choice.

Now, you can use `ghostscript` to compress your PDF file for the web:

{% code overflow="wrap" %}

```
gs -sDEVICE=pdfwrite -dNOPAUSE -dQUIET -dBATCH -dPDFSETTINGS=/screen -dCompatibilityLevel=1.4 -sOutputFile=output.pdf input.pdf
```

{% endcode %}

That’s not exactly a memorable command, so I’ve made a function that you can add to your `~/.bash_profile` to allow you to easily compress PDF files from your terminal:

{% code overflow="wrap" %}

```
# Usage: compresspdf [input file] [output file] [screen*|ebook|printer|prepress]
compresspdf() {
    gs -sDEVICE=pdfwrite -dNOPAUSE -dQUIET -dBATCH -dPDFSETTINGS=/${3:-"screen"} -dCompatibilityLevel=1.4 -sOutputFile="$2" "$1"
}
```

{% endcode %}

Now you can simply run the following command:

```
compresspdf "Massive.pdf" "Small.pdf"
```

Using this command I managed to compress an A3 size PDF (originally around 9MB) down to just under 1MB, which is perfect for the web.