An email address identifies a location to which email messages can be delivered. The first electronic mail delivery engaging two machines was done in 1971 by Ray Tomlinson, a programmer at Bolt, Beranek and Newman, an engineering company in Cambridge, Massachusetts. He needed a way to separate, in the email address, the name of the user from the machine the user was on. He wanted a character that would not, under any conceivable circumstances, be found in the user’s name. He looked down at the keyboard and chose the @ sign among various punctuation marks available on his Model 33 teletype keyboard. He had no idea that he was creating an icon for the wired world. Today, email is the most used application on the internet. Each email account has a unique address. A general format for an email address is: username@computer_name . The part before the @ sign is the local part of the address, the user name of the recipient, and the part after the @ sign is the domain part which is a host computer name.
Monthly Archives: February 2010
Running command in Linux
Commands have the following syntax:
command [options] <arguments>
- Each item is separated by space.
- Options modify commands behavior; but it’s optional.
- Single-letter options usually preceded by a hyphen –
ex: -a, -b, -ab
- Full-word options usually preceded by —
ex: --help
- Arguments are the file-names or other data needed by the command.
If you enter a command and do not get a prompt back, the command may be busy executing or may be waiting for a input. To interrupt a command taking too long to execute, press Ctrl-c.
Multiple commands can be separated by semicolon (;). You can separate multiple commands on the same line with semicolons. When the first command finishes, the next one will execute.
ex:
linux-lnz0:/home/suneil/Desktop # mkdir -v backups; cp -v *.txt backups/ mkdir: created directory `backups' `su.txt' -> `backups/su.txt' `test.txt' -> `backups/test.txt' `test1.txt' -> `backups/test1.txt' `test2.txt' -> `backups/test2.txt'
-v stands for verbose which explains what is being done.
Using WHATIS command in Linux
whatis accepts the name of another command as its only argument. It then searches for the given command name in a database of short descriptions. If it finds a match, the description is printed on your screen.
Along with the description, whatis prints the command’s name and a number in the parenthesis. This number represents represents the ‘chapter’ of the Linux Manual where more thorough documentation can be found.
The database that whatis uses is (re)generated automatically every night. This means that on newly-installed systems whatis will not work at first because the database does not yet exist. However, you can generate a database without waiting for the automatic update by running the command makewhatis as root.
Using CAL command in Linux
cal prints an ASCII calendar of the curent month. When given a single numeric argument, cal will give a calendar for the given year. Use a four digit year, however, as the command cal 10 will give a calendar for the year 10, not the year 2010.
If you give a month and year as arguments, cal command will display the calendar for that particular month. For example:
root@linux-lnz0:~ <83>#cal 02 2010 February 2010 Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Using DATE command in Linux
date command prints the system time and date. The format is configurable via an optional formatting string (see options with date –help). The following example demontrate this feature:
root@linux-lnz0:~ <76>#date Mon Feb 8 18:22:00 IST 2010 root@linux-lnz0:~ <77>#date +"Today is %A, %B %d, %Y. %nIt is %r, %Z." Today is Monday, February 08, 2010. It is 06:22:51 PM, IST.
Tricky Questions
How many of these can you get? Especially the last 4 are challenging. They are great for bars.
Q1. A murderer is condemned to death. He has to choose between three rooms: The first is full of raging fires, the second is full of assassins with loaded guns, and the third is full of lions that haven’t eaten in 3 years. Which room is safest for him?
Q2. A woman shoots her husband. Then she holds him under water for over 5 minutes. Finally, she hangs him. But 5 minutes later they both go out together and enjoy a wonderful dinner together. How can this be?
Q3. A magician was boasting one day at how long he could hold his breath under water. His record was 6 minutes. A kid that was listening said, “that’s nothing, I can stay under water for 10 minutes using no type of equipment or air pockets!” The magician told the kid if he could do that, he’d give him $10,000. The kid did it and won the money. Can you figure out how?
Q4. There are two plastic jugs filled with water. How could you put all of this water into a barrel, without using the jugs or any dividers, and still tell which water came from which jug?
Q5. What is black when you buy it, red when you use it, and grey when you throw it away?
Q6. Can you name three consecutive days without using the words Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, or Sunday?
Q7. This is an unusual paragraph. I’m curious how quickly you can find out what is so unusual about it? It looks so plain you would think nothing was wrong with it! In fact, nothing is wrong with it! It is unusual though. Study it, and think about it, but you still may not find anything odd. But if you work at it a bit, you might find out! Try to do so without any coaching!
Q8. You are participating in a race. You overtake the second person. What position are you in?
Q9. If you overtake the last person, then you are…?
Q10. (in your head!) Take 1000 and add 40 to it. Now add another 1000. Now add 30. Add another 1000. Now add 20. Now add another 1000. Now add 10. What is the total?
Q11. Mary’s father has five daughters: 1. Nana, 2. Nene, 3. Nini, 4. Nono. What is the name of the fifth daughter?
Now how many could you answer?
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ANSWERS:-
A1. The third. Lions that haven’t eaten in three years are dead.
A2. The woman was a photographer. She shot a picture of her husband, developed it, and hung it up to dry.
A3. The kid filled a glass of water and held it over his head for 10 minutes.
A4. Colour and Freeze them first. Take them out of the jugs and put the ice in the barrel. You will be able to tell which water came from which jug.
A5. The answer is Charcoal. In Homer Simpson’s words: hmmmm… Barbecue.
A6. Yesterday, Today and Tomorrow.
A7. The letter “e”, which is the most common letter in the English language, does not appear once in the long paragraph
A8. If you answer that you are first, then you are absolutely wrong! If you overtake the second person and you take his place, you are second!
A9. If you answered that you are second to last, then you are wrong again. Tell me, how can you overtake the LAST person?!
A10. Did you get 5000? The correct answer is actually 4100. Don’t believe it? Check with your calculator!
A11. Nunu? NO! Of course not. The fifth daughter is Mary. Read the question again.
Very Clever..
John lived alone in the Irish countryside with only a pet dog for company. O NE day the dog died, and John went to the parish priest and asked, “Father, my dog is dead. Could ya’ be saying’ a Mass for the poor creature?”
Father Patrick replied, “I’m afraid not; we cannot have services for an animal in the church. But there are some Baptists d o wn the lane, and there’s no tellin’ what they believe. Maybe they’ll do something for the creature.”
John said, “I’ll go right away Father. Do ya think $5,000 is enough to donate to them for the service?”
Father Patrick exclaimed, “Sweet Mary, Mother of Jesus! Why didn’t ya tell me the dog was Catholic?
Too Fast
A nice lady just called. She needed to know how it was possible that her flight from Detroit left at 8:20am and got into Chicago at 8:33am.
The Customer Care executive tried to explain that Michigan was an hour ahead of Illinois, but she could not understand the concept of time zones.
Finally the executive told her the plane went very fast, and she was convienced with that!
Observation
A medical Professor was giving lecture to a class on ‘Observation’. He took out a jar of yellow-colored liquid. “This”, he explained, “is urine. To be a doctor, you have to be observant to 4 things i.e. color, smell, sight, and taste.”
After saying this, he dipped his finger into the jar and put it into his mouth. His class watched on in amazement, most, in disgust. But as they had to prove to be good students, the jar was passed, and one by one, they dipped one finger into the jar and then put it into their mouth.
After the last student was done, the Professor shook his head in disappointment had said “If any of you had been observant, you would have noticed that I put my 2nd finger into the jar and my 3rd finger into my mouth.”
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