Concatenating PDF files on Linux

Sometimes, as an adult in this increasingly-digital world, you need to do things with PDF files.

For example, I sometimes need to stick a bunch of PDFs together into one extra long PDF. This is useful, for example, if you want to keep a digital copy of an invoice and your proof of payment together in one file. Or maybe you scanned, photographed, or screenshotted the 5 pages of a document separately and want to stick them together into one.

On Linux, this can be done on the command line using a program called Ghostscript. Ghostscript is a program for working with Postscript and PDF files.

Ghostscript is powerful, but has many options and I struggle to remember exactly how to run it correctly. That's why I wrote this little concat-pdf.sh shell script to simplify my life.

Save this as concat-pdf.sh wherever you keep your personal shell scripts (~/bin/ can be a good option) and make it executable.

#!/bin/bash

# Concatenates PDFs together
#
# Usage: concat-pdf.sh <target> <file..>
#
# Requires ghostscript to be installed and on the path.

set -e

display_usage() {
    echo "Usage: concat-pdf.sh <target> <file..>"
}

if ! command -v gs &> /dev/null
then
    echo "Ghostscript must be installed with gs on the path"
    exit 1
fi

if [ $# -lt 2 ]
then
    display_usage
    exit 1
fi

TARGET_PDF=$1;

if [ -e "$TARGET_PDF" ]
then
    display_usage
    echo "$TARGET_PDF already exists"
    exit 1
fi

gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -sOutputFile="$@"

Example of using the script:

concat-pdf.sh new-pdf-file.pdf pdf-part-1.pdf pdf-part-2.pdf