Question

i want create simple application for notification in ubuntu…
For example: in 18:00, 21:00, 24:00 i want to receive message from ubuntu

simple method for message is:

def alarm
  %x{notify-send -i rhythmbox Test "Hello world" }
end

alarm

and when i sart this file ( like: ruby somefilename.rb )

i got notification message.

Question: how to cause this file run in 18:00, 21:00, 24:00

PS I know that there are many similar programs (for the experience like to know how to do that)

U.D. Using crontab:

* * * * * %x{notify-send -i rhythmbox Test "Hello world" }

Every minutes should start this script – but nothing happend

in some examples i saw that instead of script we put path to them: something like this:

* * * * * ruby /home/Home/myDisk/somefile.rb

how open with ruby this file or launch notify-send script in terminal without ruby ?

Answer 1

Good tools are cron and anacron.

To do it in Ruby, one way is to use the Ruby sleep method:

seconds = 18 * 60  # 18 minutes * 60 seconds/minute
sleep(seconds)
alarm

To use your “wake up” times in a loop:

start = Time.now
for wake in [18, 21, 24]
  seconds = wake * 60 + start - Time.now
  sleep(seconds)
  alarm
end

Also see Ruby Thread to do alarms in parallel:

for wake in [18, 21, 24]
  threads << Thread.new(wake) {|wake|
    sleep(wake * 60)
    alarm    
  }
end
threads.each {|t| t.join }