When your black cartridge is empty and your printer driver doesn't help, change the pdf from black to something else :D

print_in_color.sh

#!/bin/bash 

# From https://www.reddit.com/r/linux4noobs/comments/2yzld7/command_line_change_text_color_in_pdf/
# It will go through all the pdfs in the directory and change the color black (0 0 0) to something else (0.3 0.3 0.3)
# The RGB values here go from 0 to 1 instead of 0 to 255 ;)

for f in *.pdf; do
  echo $f
  pdftk "$f" output "tmp-$f" uncompress
  sed -i "s/0 0 0 rg/0.3 0.3 0.3 rg/g" "tmp-$f"
  sed -i "s/0 0 0 RG/0.3 0.3 0.3 RG/g" "tmp-$f"
  pdftk "tmp-$f" output "filled-$f" compress
  rm "tmp-$f"
done