Interactive calendar for your console. Allows to scroll through the calendar interactively. Uses `cal` utility to print the calendar.

ical.sh

#!/usr/bin/env sh

# Interactive cal
#
# Allows to scroll through the calendar interactively.
# Uses `cal` utility to print the calendar.
#
# © Michael Klimenko

set_current_date() {
  Y=$(($(date +"%Y") + 0))
  M=$(($(date +"%-m") + 0))
}

normalize_date() {
  ((M == 0)) && M=12 && ((Y--))
  ((M == 13)) && M=1 && ((Y++))
}

read_key() {
  read -sn1 key # 1 char (not delimiter), silent
  read -sn1 -t 0.0001 k1 # This grabs all three symbols 
  read -sn1 -t 0.0001 k2 # and puts them together
  read -sn1 -t 0.0001 k3 # so you can case their entire input.

  key+=${k1}${k2}${k3}
}

prev_month() {
  ((M--))
  normalize_date
}

next_month() {
  ((M++))
  normalize_date
}

set_current_date

while true
do
  clear
  cal -3 $M $Y

  read_key
  case "$key" in
#    k|$'\e[A'|$'\e0A')  # up arrow
#        echo up;;

#    j|$'\e[B'|$'\e0B')  # down arrow
#        echo down;;

    l|$'\e[D'|$'\e0D') # left arrow
        prev_month;;

    h|$'\e[C'|$'\e0C')  # right arrow
        next_month;;

    $'\e[1~'|$'\e0H'|$'\e[H') # home key:
        set_current_date;;

#    $'\e[4~'|$'\e0F'|$'\e[F') # end key:
#        echo end;;

    q|'') # q, CR: quit
        echo Bye!
        exit;;
  esac
done