A bash script that schedules a desktop notification sometime later.

remindme

#!/usr/bin/env bash

# USAGE:
# remindme {WHEN} {REMINDER MESSAGE}
# - The first argument must be compliant with DATE(1) and defines when to remind you.
# - The following arguments are a message to be delivered in a desktop notification.
#
# Examples:
#   remindme tomorrow Write an e-mail to John Doe
#   remindme '20160705 17:25' Call Jane Doe


# Display the notification during this amount of milliseconds:
NOTIFICATION_DURATION=20000

set -e

delay=$1
shift
message=$*

if [[ $delay == ?(-)+([0-9]) ]]; then
    delay="$delay minutes"
fi

reminder_delay=$(( $(date -d "$delay" +'%s') - $(date +'%s') ))
echo "You will be reminded of this on $(date -d "$delay") unless you shutdown your computer in the meantime."
(
    sleep "$reminder_delay"
    notify-send -t "$NOTIFICATION_DURATION" "$message"
) &