This is very similar to the traditional leave command-line utility,
with a few enhancements:
- Custom reminder messages instead of simply “Time to leave.”
- Plays a distinctive quack sound on the computer’s speaker. (No other program quacks for attention, so if my computer quacks, I know it must be reminding me of something significant.)
- Time is specified using the unambiguous 24-hour clock, so no more am/pm confusion.
- Can schedule reminders relative to the current time (e.g. 20 minutes from now) as well as at a specific absolute time of day.
- Can list the process ID’s of all pending alarms.
- Tries as hard as possible to work around how processor sleep states caused by power management affect sleeping and alarms.
Quack builds on both MacOS and Linux. With a few minor changes to
list.c and quack.c, it should build on most fully POSIX-compliant
operating systems. (Quack relies on certain particulars of how
POSIX-compliant kernels launch and manage processes, so will not run
properly on Windows. Sorry.)
To build, just type:
make -f Makefile.linux
or:
make -f Makefile.macos
You will then have to install quack.mp3 (MacOS) or quack.ogg (Linux)
in your home directory’s misc subdirectory. If you want this file to
be kept elsewhere, change the logic in quack.c before building.
A C compiler, a sound card, and on Linux the paplay command must be
installed.
quack help will print out a brief summary of allowed syntax. Some
examples follow:
A lunchtime reminder:
quack at 12:00 LUNCH
To check the oven in 15 minutes:
quack in 15 Check on cookies
By default quack reminds you five minutes before, one minute before, at
the requested time, and every minute thereafter for up to 10 times. To
make it shut up, run quack list to determine the ID of the quack
process and then kill it.
If you only want a single alert, use the once modifier:
quack once in 5 Check again
Times are specified in hh:mm format. For quack at times are on a
24-hour clock, and both hours and minutes must be specified; the alarm
will always be set for a time in the next 24 hours. For quack in,
times are specified as a number of hours and minutes in the future, with
the hours portion optional.
quack list will list all running quack processes, which is useful if
you want to silence a given alarm (i.e. kill its process).
The way to silence an alarm is to kill its associated process. See
“Listing Processes” immediately above. If you log out or close the
window associated with one or more quack processes, it will also
silence the associated alarms.
This is something of a problem. If a computer goes to sleep, it cannot
issue alarms. The cure is to configure power management so that your
computer never goes into a deep sleep if receiving alarms is important
to you. (This problem is not particular to quack; it affects any
program whose job it is to issue asynchronous reminders.)
A further wrinkle is that if a computer goes to sleep, time essentially
ceases to pass so far as the alarm(2) system call (which is what quack
uses under the hood) is concerned. This causes many alarm clock programs
(and the traditional leave command) to issue alerts which are late by
the amount of time the processor spent in a deep sleep state. quack
works around this glitch by doing its sleeping in short “naps,”
awakening at regular intervals to check the current time. So long as
your computer is not in a deep sleep at the scheduled time of the alarm,
the alarm should get raised on time or close to it.