PDF merging utility.

# To merge two PDFs:
pdfjoin <file1> <file2> --outfile <output_file>

# To save pages 3 to 5 followed by page 1 to a new PDF:
pdfjoin <file 3-5,1> --outfile <output_file>

# To merge subranges from two PDFs:
pdfjoin <file1 3-5,1> <file2 4-6> --outfile <output_file>