Handy UNIX Commands – An Ongoing Collection

Mostly solaris, probably similar on other *nix sytems….

Disk Stats

$ iostat -xnct 5
tty         cpu
tin tout  us sy wt id
3   42  45  1  0 54
extended device statistics
r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device
0.4    3.8   11.6   23.5  0.0  0.0    2.1    1.1   0   0 c1d0
0.0    0.0    0.0    0.0  0.0  0.0    0.0    0.0   0   0 c0t0d0
tty         cpu
tin tout  us sy wt id
187  180  54  4  0 43
extended device statistics
r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device
0.8    6.4    5.0   80.2  0.0  0.0    0.1    1.1   0   1 c1d0
0.0    0.0    0.0    0.0  0.0  0.0    0.0    0.0   0   0 c0t0d0

tty         cpu
tin tout  us sy wt id
14  277  50  1  0 49
extended device statistics
r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device
0.0    1.4    0.0   12.8  0.0  0.0    0.1    0.3   0   0 c1d0
0.0    0.0    0.0    0.0  0.0  0.0    0.0    0.0   0   0 c0t0d0

The days are getting shorter – Perl Script to Calculate Sunrise and Sunset

Hi Everyone;

I made a great perl script to calculate sunrise and sunset times in Toronto for the whole year with a graphical output. I wrote this in my dead-time during a work order tonight… so I hope you enjoy it as much as I enjoyed making it.

Notes:

• my brother’s birthday, which is right around the corner is day 286.  That’s a g33ky number.
• Here’s a day-of-the-year number calendar .
• does not account for Daylight Savings Time changes
• the output is in decimal form (.1 hours is about 6 minutes)

How to understand the output

————-***********************————–      Day: 286 , sunrise: 7.46371983255512 , sunset: 18.6748421708946 

•  
  • The —– is darkness (night)
  • The ******* is sunlight (day)
  • sunrise 7.46371….  is the time local to toronto at GMT -4 (7.46 = 7 oclock + (.46 * 60 minutes) = 7:27am

 

Sample output.  If you scroll through enough lines, an “hourglass” shape starts to appear:

# ./sun.pl
----------------******************----------------      Day: 1 , sunrise: 8.8499964506844 , sunset: 17.8363243941365 
----------------******************----------------      Day: 2 , sunrise: 8.85157917721863 , sunset: 17.8505635052382 
---------------*******************----------------      Day: 3 , sunrise: 8.85247026342554 , sunset: 17.8653183755327 
---------------*******************----------------      Day: 4 , sunrise: 8.85266811641787 , sunset: 17.8805734993673 
---------------*******************----------------      Day: 5 , sunrise: 8.85217187255689 , sunset: 17.8963130190473 
---------------*******************----------------      Day: 6 , sunrise: 8.8509813847397 , sunset: 17.9125207658933 
---------------*******************----------------      Day: 7 , sunrise: 8.84909720761213 , sunset: 17.9291803019326 

Here’s the perl code to support it.  A lot of it was based on http://www.adventist.org/sun/sun.pm .  Obviously, i did a lot of reworking of the ideas into my own script.  Click MORE for a special suprise (and the code)

Voyager 2 – Still Out There, Still Doing It’s Job

Probably the most awesome peice of hardware out there is still out there, and still doing it’s job. The Voyager 2 space probe is powered, and happily sailing along deeper and deeper into outer space.

To this day, NASA employs staff to send command instructions and to receive scientific and telemetry data that Voyager is still sending.

Voyager II was launched on August 20, 1977 to explore Jupiter, Saturn, Uranus, Neptune, and Pluto, then to continue in interstellar space. After having visited Pluto in 1989, every planet in the Solar system has been visited at least once.

Voyager Weekly reports of the activities are available from NASA. Items include details such as how much electricity and propellant are still available, and also telemetry information, like how far away from earth, how fast it’s travelling and how long a signal takes to reach it. Here’s an example from this week:

• Distance from the Sun (Km) 12,788,000,000
• Distance from the Earth (Km) 12,814,000,000
• Velocity Relative to Earth (Km/sec) 23.150
• Generator Output (Watts) 284.2
• Voyager 2 command operations consisted of the uplink of seven bracketed Command Loss Timer Resets sent on five-minute centers using 0.5 Hz steps on 03/26 [DOY 086/2007z]. The spacecraft received three of the seven commands sent.
• There were 53.6 hours of DSN scheduled support for Voyager 2 of which 1.2 hours were large aperture coverage. There were no real-time or schedule support changes made or significant outages during the period.
• Science instrument performance was nominal for all activities during this period. The EDR backlog is 2 day.

Isn’t it incredible how far away Voyager 2 is ? Even at the speed of light, round trip time for radio communications is almost 24 hours. Can you imagine sending a simple instruction to Voyager 2 and not expecting a response until tommorow at this time? Insane! Nowadays, the signal is travelling so far and is so distorted that only half of the commands are ever understand and responded to.

A fantastic document about Voyager 2 with a fun flip-page animation!

Print out all 178 pages (duplex if you can) and you will have an awesome document for reading! The flip-page animation is in the lower left corner and looks like this:

I found this document hunting around the NASA web page. It was written in 1985 about the January 1986 fly-by of Uranus. True history was made with Voyager, because very little was known about Neptune at the time. For example, the guide mentions “one of the five presently known moons of Uranus”, however, after Voyager flew by we now know of 27.

To summarise, simply from telemetry ( reducing Voyager to a simple talking projectile ), we are learning so much about our galaxy and the reach of our Sun. For more information check out this article on the Heliopause, the boundry that seperates our solar system from interstellar space. Thanks Voyager. I know you’ll be out there for a millennial’s worth of human generations.

This document makes a great nighttime reader. Print out a copy. Here’s the index so you know what to expect. Forgive the spaces, but OCR can only do so much.:

1. Introduction
Voyager’s Past
Anticipating Uranus

2 . Uranus
Overview of t h e Planet
The Atmosphere of Uranus
The Magnetosphere of Uranus
The Satellites of Uranus
The Rings of Uranus

3 . Getting The Job Done
Planning
Sequencing
Flight Operations
Commanding
Receiving Data
The Results

4 . Scientific Objectives
Imaging Science Subsystem (ISS)
Infrared Interferometer Spectrometer and Radiometer (IRIS)
Ultraviolet Spectrometer (UVS)
Photopolarimeter Subsystem (PPS)
Radio Science Subsystem (RSS)
Fields and Particles Experiments
Planetary Radio Astronomy (PRA)
Magnetometer (MAG)
Particle Detectors
Plasma Subsystem (PLS)
Low-Energy Charged Particle (LECP)
Cosmic Ray Subsystem (CRS)
Plasma Wave Subsystem (PWS)
Sensor Engineering Characteristics
The Physics of the Optical Target Instruments
Science Links

5 . Voyager Spacecraft
The High Gain Antenna
Spacecraft Attitude Control
Spacecraft Maneuvers
Scan Platform
Spacecraft Power Subsystem
Digital Tape Recorder
The Spacecraft Receiver
The Computer Command Subsystem
The Flight Data Subsystem
The Science Instruments

6. Mission Highlights
Pre-Encounter Test and Calibration Activities
Observatory Phase (OB)
Far Encounter Phase (FE)
Critical Late Activities
Near Encounter Phase (NE)
Post Encounter Phase (PE)
Contingency Sequences
Cruise to Neptune

7 . What’s New
Maintaining a Strong Signal
Discarding Unnecessary P i c t u r e Data
More Accuracy for Fewer B i t s
Taking Good Pictures in Feeble Light Levels
Big Changes in t h e Deep Space Network
The Bottom Line

8. Gee-whiz Facts
Overall Mission
Voyager Spacecraft
Navigation
Science
The Future

9 . How Far and How Fast
The Great Escape
Voyager 2 a t Uranus
Key Events. Distances. and Speeds

10 . Jupiter and Saturn Highlights
Jupiter
Jupiter’ s Rings
Jupiter ‘ s Moons
Jupiter ‘ s Magnetosphere
Saturn
Saturn ‘ s Rings
Saturn’ s Moons
Saturn’ s Magnetosphere

Kindergarten Google – A to Z and 1 to 10

Have you ever taken the time to see exactly what the A to Z search on Google comes back with? We start by simply typing in a single letter on Google and seeing what the first return is. For the most part, we find a notable pattern, but with a few bizarre oddities:

• Sometimes, an article on Wikipedia is referenced “ie, an article on the letter ‘b’ “
• There are a few stock symbols
• Many mathematical constants

Funny items

• The letter “S” brought up Queen’s University… huh?
• The letter R brought up a project that’s commonly referred to as the “S” project
• There’s a little bit of toilet humour under “P”

I thought of this article a while back, but seems like a good waste of time to me! Let’s begin!

Section 1 : A to Z

A – Links in HTML documents The destination anchor of a link may be an element within an HTML document. … When the A element’s href attribute is set, the element defines a source

B – B – Wikipedia, the free encyclopedia B is the second letter in the Latin alphabet. Its name in English is spelled bee or occasionally be (pronounced /biː/), plural bees.

C – the speed of light = 299 792 458 m / s

D – DOMINION RES NEW (NYSE)

43.38 -0.04 (-0.09%) 23 Apr 9:43am ET
Open: 43.42 High: 43.42 Low: 43.15		Volume: 121,193 Avg Vol: 2,889,000 Mkt Cap: 25.04B

E -

e = 2.71828183

Ancient BBS Receipt for our Atari 1040ST. Canada Remote Systems.

A nostalgic view from history (I call 1988 history).

Know how everyone pays for internet access? Back in the day, we used to pay for BBS access.

What’s a BBS? It’s another computer that you dial up to in order to download files, post messages (kind of like email between users of the same system).

The ATARI 1040ST was not exactly our first computer, but it was our first computer with a MOUSE! It was kicking the shit out of any machine any school-chum we knew had? Why?

1. PC’s were clunky, iron, and only in monochrome. We had 256 SCREAMIN’ COLOURS!
2. It wasn’t a video game system, it was a shit-kicking GUI OS (looking similar to the modern Macintoshes and Amiga’s owinng to the the Motorola 68000 chips that were used in Macs until the late 90’s)
3. 3.25″ FLOPPY!!!!! MEGA STORAGE (DoubleDensity)
4. It had F1-F12 keys that were angular !!!! F12 baby!
5. We had an AWESOME 300 baud cup-modem. Downloading a file? SHHHHHH…. quietly walk out of the room, and gently close the door behind you. For a few hours.
6. It had a kick-ass serial port that my DAD made a home-made serial cable for to retrieve his old word-star files from his Kaypro IV.
7. It worked with the daisy-wheel printer we had leftover from the Kaypro.

Our favourite games were “NeoPaint”, “Mercenary (with the X-rated credit, so dad would send us out of the room while the game loading credits were off-screen) and some kind of game , I think called “Mud Pies” where you used to run around throwing pies at everyone.

I think CRS was great, because it was the first time we got to communicate to the outside world with our computer! WOW! computers could use the phone lines. Amazing. They had all kinds of files (we kept our membership even when we moved over to a portable 286 laptop a little later on). They had local numbers in our region too.

Anyways, thanks dad for giving us a jump start.

It’s amazing what $65.00 in 1988 money would buy for a year.

Deep-Space Data Transmission = Free Storage!

Delays. Delays. Delays. Not all bad, but some better than others.

Ordinarily, in the data world, a delay is a loathsome thing. It makes your conversations on the cell phone sound strange and impersonal, it turns your favourite video first-person shoot-em-up video game skills look like a n00b, and it’s why the people across the street from you with Cable TV are jumping with joy a few seconds before you with your Satellite TV when the Blue Jays win another World Series.

What about extra-terrestrial data communications?

The satellite used for Bell ExpressVu or other TV providers is a very small distance away from earth, but even so, this adds a small delay to the digital signal you receive. A satellite in Geostationary orbit must be at an altitude of 35,786 km (22,240 statute miles).

Light travels 1,079,252,848.8 km/h, or, 17 987 547.5 km/second.

Therefore, the delay is 0.00198948745 seconds, or, about 4 milliseconds 2-way, plus processing delay. This might seem small , but keep in mind that a delay of 200 milliseconds renders 2-way conversation unusable in full duplex (ie. it’s time to talk in half-duplex like walkie-talkies). Human perception can recognise 50 milliseconds of delay.

So back to my claim of free storage. What happens to that data for the 2 seconds it is en-route from the earth to the sattelite? It’s neither at the transmitter, nor is it at the receiver. This data is in transit as an electromagnetic wave. It’s intact, coherent, but isn’t anywhere to be found!

Exactly how much data is in the “ether” between the earth and a satellite at any given point in time? Lets build some numbers to work with:

Speed of electromagnetic propogation: 17 987 547.5 km/second
Frequency of Ku Band transmission: ~ 12.7GHz (12 700 000 000 oscilations per second).

One oscillation of a frequency is equivalent to 1 bit. For our purposes, I’m going to ignore things like headers, preamble, checksums, and the “good morning vietnam” that surrounds, encompases, and trails deep-space transmission of data.

Dividing the time required to reach the Satellite by the frequency of the transmission, we can see that there are 25,266,490 bits suspended in the ether between the satellite and the ground station. Equating that to a file, we can safely say that we have”stored” a 3MB file without the use of a wire, a hard drive, a flash memory drive, or any physical device.

This is all well and good, but our “storage” seems to expire pretty quickly. In 2 ms, our data is removed from this storage medium until the next time it is spit out there. Useless, right? Not quite. What if we could position 2 satellites to constantly rebound this data off of eachother, and when we need the data, we issue a command to the satellite to copy the data over to us the next time it comes around?

—->
<—-
—->
<—-

The further we move the satellites apart from each other, the more data we can fit into this constant cyclical stream, thanks to delay.

So how far apart do we have to move the satellites in order to store, say, a DVD movie, or the entire user database of Facebook? Here’s a few examples with a relay that begins at earth. I’m going to only include the data going in one direction.

Earth to …	Distance	Delay (seconds)	Data (Mbits)	Equivalent Amount of Data
Satellite in GeoStationary Orbit	35,786 km	0.00198948745	25.2	MP3 song
Moon	384,400km	0.0213703397	256	Quicktime Program Installer
Mars	228,000,000 km	12.6754356	152105	5 DVD Movies
Voyager 1	15,500,000,000 km	861.707245	1.03404869 × 1013	Entire Wikipedia Database

So I guess that the entire contents of all the hard drives of the world (the Internet) can be transmitted before it arrives at our nearest star, which is 40,000,000,000,000 km’s away (give or take a few).