beep - Online in the Cloud

PROGRAM:

NAME

beep - beep the pc speaker any number of ways

SYNOPSIS

beep [--verbose | --debug] [-e device | --device device] [-f N] [-l N] [-r N] [-d N] [-D
N] [-s] [-c]

beep [ OPTIONS ] [-n] [--new] [ OPTIONS ]

beep [-h] [--help]

beep [-v] [-V] [--version]

DESCRIPTION

beep allows the user to control the pc-speaker with precision, allowing different sounds
to indicate different events. While it can be run quite happily on the command line, it's
intended place of residence is within shell/perl scripts, notifying the user when
something interesting occurs. Of course, it has no notion of what's interesting, but it's
real good at that notifying part.

All options have default values, meaning that just typing 'beep' will work. If an option
is specified more than once on the command line, subsequent options override their
predecessors. So 'beep -f 200 -f 300' will beep at 300Hz.

OPTIONS

--verbose, --debug
enable debug output. This option prints a line like the following before each beep:

[DEBUG] 5 times 200 ms beeps (100 delay between, 0 delay after) @ 1000.00 Hz

-e device, --device device
use device as event device. If the switch isn't used, /dev/tty0 and /dev/vc/0 are
tried in turn.

-f N beep at N Hz, where 0 < N < 20000. As a general ballpark, the regular terminal
beep is around 750Hz. N is not, incidentally, restricted to whole numbers.

-l N beep for N milliseconds.

-r N specify the number of repetitions (defaults to 1).

-d N, -D N
specify a delay of N milliseconds between repetitions. Use of -d specifies that
this delay should only occur between beeps, that is, it should not occur after the
last repetition. -D indicates that the delay should occur after every repetition,
including the last. Normally, -d is what you want, but if, for example, you are
stringing several beep commands together to play the star wars anthem, you may want
control over every delay.

-n, --new
this option allows you to break the command line up into specifying multiple beeps.
Each time this option is used, beep starts treating all further arguments as though
they were for a new beep. So for example:

beep -f 1000 -n -f 2000 -n -f 1500

would produce a sequence of three beeps, the first with a frequency of 1000Hz (and
otherwise default values), then a second beep with a frequency of 2000Hz (again,
with things like delay and reps being set to their defaults), then a third beep, at
1500Hz. This is different from specifying a -r value, since -r repeats the same
beep multiple times, whereas -n allows you to specify different beeps. After a -n,
the new beep is created with all the default values, and any of these can be
specified without altering values for preceding (or later) beeps. See the EXAMPLES
section if this managed to confuse you.

-s, -c these options put beep into input-processing mode. -s tells beep to read from
stdin, and beep after each newline, and -c tells it to do so after every character.
In both cases, the program will also echo the input back out to stdout, which makes
it easy to slip beep into a text-processing pipeline, see the EXAMPLES section.

-h, --help
display usage info and exit

-v, -V, --version
display version information and exit

EXAMPLES

At its simplest (yet still effective)

beep

A more interesting standalone setup

beep -f 300.7 -r 2 -d 100 -l 400

As part of a log-watching pipeline

tail -f /var/log/xferlog | grep --line-buffered passwd | \
beep -f 1000 -r 5 -s

When using -c mode, I recommend using a short -D, and a shorter -l, so that the beeps
don't blur together. Something like this will get you a cheesy 1970's style beep-as-you-
type-each-letter effect

cat file | beep -c -f 400 -D 50 -l 10

A highly contrived example of -n/--new usage

beep -f 1000 -r 2 -n -r 5 -l 10 --new

will produce first two 1000Hz beeps, then 5 beeps at the default tone, but only
10ms long each, followed by a third beep using all the default settings (since none
are specified).

IOCTL WACKINESS

Some users will encounter a situation where beep dies with a complaint from ioctl(). The
reason for this, as Peter Tirsek was nice enough to point out to me, stems from how the
kernel handles beep's attempt to poke at (for non-programmers: ioctl is a sort of catch-
all function that lets you poke at things that have no other predefined poking-at
mechanism) the tty, which is how it beeps. The short story is, the kernel checks that
either:

- you are the superuser

- you own the current tty

What this means is that root can always make beep work (to the best of my knowledge!), and
that any local user can make beep work, BUT a non-root remote user cannot use beep in it's
natural state. What's worse, an xterm, or other x-session counts, as far as the kernel is
concerned, as 'remote', so beep won't work from a non-privileged xterm either. I had
originally chalked this up to a bug, but there's actually nothing I can do about it, and
it really is a Good Thing that the kernel does things this way. There is also a solution.

By default beep is not installed with the suid bit set, because that would just be zany.
On the other hand, if you do make it suid root, all your problems with beep bailing on
ioctl calls will magically vanish, which is pleasant, and the only reason not to is that
any suid program is a potential security hole. Conveniently, beep is very short, so
auditing it is pretty straightforward.

Decide for yourself, of course, but it looks safe to me - there's only one buffer and
fgets doesn't let it overflow, there's only one file opening, and while there is a
potential race condition there, it's with /dev/console. If someone can exploit this race
by replacing /dev/console, you've got bigger problems. :)

So the quick, only, and likely safe solution if beep is not beeping when you want it to is
(as root):

# chmod 4755 /usr/bin/beep

(or wherever you put it)

The one snag is that this will give any little nitwit the ability to run beep successfully
- make sure this is what you want. If it isn't, a slightly more complex fix would be
something like:

# chgrp beep /usr/bin/beep

# chmod 4750 /usr/bin/beep

and then add only beep-worthy users to the 'beep' group.

FREQUENCY TABLE

Several people have asked for some basic help translating music notes to frequencies.
There are a lot of music notes, and several tables online will give you translations, but
here are approximate numbers for the octave of middle C, to get you started.

Note Frequency
C 261.6
C# 277.2
D 293.7
D# 311.1
E 329.6
F 349.2
F# 370.0
G 392.0
G# 415.3
A 440.0
A# 466.2
B 493.9
C 523.2

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