shell script to print a calendar to the screen, highlighting today (geektool)

calendar.sh

#!/bin/sh 
# useful for [geektool](http://projects.tynsoe.org/en/geektool/)
# 
# colorcal - change current day and date via ANSI color escape sequences 
# see http://www.termsys.demon.co.uk/vtansi.htm for color codes. 

color="\033[1;33m" 
underline="\033[4m" 
reset="\033[0m" 

# get day & date 
current_day=`/bin/date "+%a" | cut -b 1,2` 
current_date=`date | awk '{print $3}'` 

#color em. 
color_day=`echo "${underline}${current_day}${reset}"` 
color_date=`echo "${color}${underline}${current_date}${reset}"` 

# format cal output so the sed replacements work at begining and end of cal output. 
function calendar { 
/usr/bin/cal | sed 1d | sed 's/ /_/g' | sed -e 's/^/ /' -e 's/$/_/' | sed 's/_/ /g'
} 

# run calendar & substitute colored day & date. 
calendar | /usr/bin/sed -e "s/ ${current_day} / ${color_day} /" -e "s/ ${current_date} / ${color_date} /" 
# END of colorcal 

Came up with the following recipe for a colorized calendar in geektool.