xmas.sh

#!/bin/bash
#
# Prints the days remainig until Christmas onto an image and (optionally)
# sets it as the user's Twitter avatar.

avatar="avatar.png"
date="25 Dec"
user=

while getopts 'a:d:u:' flag; do
  case "${flag}" in
    a) avatar="${OPTARG}" ;;
    d) date="${OPTARG}" ;;
    u) user="${OPTARG}" ;;
    *) error "Unknown argument ${flag}" ;;
  esac
done

days="$(( $(date --date="$date" +%j) - $(date +%j) ))"

if [[ $days -lt 10 ]]; then
  text="$days!"
else
  text="$days"
fi

convert \
  -gravity SouthWest \
  -pointsize 72 \
  -stroke "#000" -strokewidth 2 -fill "#fff" -draw "text 0,0 '$text'" \
  $avatar tmp_$avatar

if [[ ! -z $user ]]; then
  curl \ #-v --compressed \
    -X POST \
    -F "image=$(base64 -w0 tmp_$avatar)" \
    -u $user \ 
    "https://foauth.org/api.twitter.com/1.1/account/update_profile_image.json"
fi