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Guitar/Picking and Plucking

There are two major methods of right hand (for right handed players) techniques namely, either by using a pick (also called a plectrum) or fingers. The plectrum is very common in rock, country and pop music, where it is considered convenient for strumming and louder guitar sound. Use of fingers is most common among classical guitarists and flamenco players, as combination of strings better executed using the right hand fingers, and generally have softer sound than the pick. Other than classical guitarists and flamenco players, use of a pick or fingers is a matter of personal preference.

Using a pick
The primary advantages of the pick are its speed, its ease of striking large chords and, because the fingernails and fingertips are not involved, its preservation of player's picking hand. Furthermore, use of a pick makes a louder and brighter sound. Its primary disadvantage is its imprecision, making muting strings necessary. Also, if the player wishes to switch to the tapping style, he or she can tap with or with out the pick: to tap with the pick just put it on its side and tap it on the desired fret. However, tapping with a pick makes it harder to tap on multiple strings.

Finger Strumming
Players wishing not to use a pick may try finger strumming. This is accomplished by holding the picking hand's first finger to the thumb, much as one might hold a pick, and striking the strings with the first fingernail. Another way is to do all down strokes with the thumb and all upstrokes with the index finger; like one is 'petting' the strings.

Apoyando Strikes
Apoyando, or splinter rested, involves the finger picking through a string such that the finger stops when resting on the next string. This technique produces a strong, loud tone, and is considered the opposite of Tirando.

Tirando Strikes
When performing a tirando, or shooting splinter strike, the finger does not affect the next string at all. This is the opposite of apoyando.

Fingerpicking
Fingerpicking is a method of playing the guitar where you use your thumb and at least one other finger to pick or pluck notes, using your fingernails, fingerpicks or fingertips. Talented players can use all five fingers on their picking hand, but many players only use four fingers and use their pinky finger as a brace on the guitar. Most classical guitarists alter the shape of their picking hand fingernails for the purpose of producing a desired sound, however this is not necessary in non-classical music; one can purchase fingerpicks to fit on the hand.

Generally fingerpicking involves picking through chords organized in a melody. Fingerpicking is used extensively in folk guitar and classical guitar, but it is also common in other genres.

Fingerpicking is surprisingly easy on an electric guitar, which is strange because fingerpicking is often regarded as an acoustic style. The player may hold his or her picking hand's fourth finger against the right edge (left edge on a left-handed guitar), and if it is held straight and steady, this technique may be used to brace the hand. This technique is called anchoring, and is frowned upon by some players. It is possible on acoustic guitars by using the bridge similarly, but this is not as effective as it will deaden the sound. Classical guitarists never anchor while playing.

When strumming with individual fingers, general rule is move the wrist only if the thumb is used, while if any other finger is used, only said finger will be used.

When you start trying to learn, your finger coordination will be terrible and it is easy to be discouraged. It takes several weeks to let your muscles develop, but if you practice using all your fingers at once your overall dexterity will increase much faster.

Classical picking
In classical guitar repertoire, there will be a "PIMA" marking for the picking hand fingers (right hand for right handed players), which indicate which finger to use: These four are the ones that are used most frequently. Sometimes, the fourth finger is used, in which it is marked either C, X or E.
 * Pulgar, or thumb.
 * Indice, or index finger.
 * Medio, or middle finger.
 * Anular, or ring finger.

Typically, the thumb has a down-picking motion and the fingers have an up-picking motion.

Clawhammer and frailing
Clawhammer, sometimes known as frailing, is a method generally used with the five-string banjo and is characteristic of traditional Appalachian folk music of the U.S. It is primarily a down-picking style, and the hand assumes a claw-like shape and the strumming finger is kept fairly stiff, striking the strings by the motion of the hand at the wrist and elbow, rather than a flicking motion by the finger. Typically, only the thumb and second or first finger are used and the finger always downpicks, flicking the string with the back of the fingernail.

A common characteristic of clawhammer patterns is the thumb does not pick on the downbeat, as one might in typical finger-picking patterns for guitar. For example, this is a common, basic time signature|2/4 pattern:
 * 1) Pick a melody note on the downbeat (quarter note)
 * 2) On the second beat (music)|beat, strum a few strings with your strumming finger or brush with all fingers (roughly an eighth note)
 * 3) Immediately following (on the second half of this beat), pick a note with the thumb, usually the shorter fifth string. (roughly an eighth note)

Here, the thumb plays the high drone (fifth string) on the second "and" of "one and two and". This combined with the second finger strumming provides a characteristic "bum-ditty bum-ditty" sound.

Some people, however, make a distinction between frailing and clawhammer:
 * In frailing, the first fingertip is used for up-picking melody, and the second fingernail is used for rhythmic downward brushing.
 * In clawhammer, only downstrokes are used, and they are typically played with one fingernail as is the usual technique on the banjo.

Travis Picking
Another well known style of finger picking is called Travis picking, named after Merle Travis who was a country singer known for his legendary picking skills. When picking, you use your thumb and first finger to hit notes at the same time, creating a double stop or interval, and then continue picking with the first finger. Usually the thumb is responsible for picking the bass line, while the first/second finger is for melody. Skilled players can carry two separate melodies with the upper and lower strings.

You can create impressive rhythms playing with just your thumb and first finger, but to really become talented you must practice using more fingers. For example, Chet Atkins expanded to use all three fingers, with thumb for bass line.

Rasgueado
The rasgueado or splinter striking technique originated from Spanish flamenco music, and usually refers to three or four fingers and sometimes the thumb striking the strings in quick succession. The notes quickly follow one another and produce a "rattling" or cascading effect.

Scruggs style
Scruggs-style finger-picking is a syncopated, five-string banjo style used in bluegrass music. It is played with thumb, first and second fingers; the fourth and/or third fingers are typically braced against the head of the instrument. The strings are picked rapidly in repetitive sequences or rolls; the same string is not typically picked twice in succession. Melody notes are interspersed among arpeggios, and musical phrases typically contain long series of staccato notes, often played at very rapid tempos. The music is generally syncopated, and may have a subtle swing or shuffle feel, especially on mid-tempo numbers. The result is lively, rapid music, which lends itself both as an accompaniment to other instruments and as a solo.

Scruggs style picking was popularized by Earl Scruggs in the early 1940's in rural North Carolina.

Tapping
Tapping is a style of playing where notes are created by quickly pressing, or tapping, the string down on the fret that you want to play. Usually tapping involves both hands, and most often it is on an electric guitar. It is possible to tap on an acoustic, but you cannot hear the notes as clearly as on an electric.

title: Guitar/Picking and Plucking


text:
Lucid Dreaming/Reality Checks/Vision

Presentation
With the vision reality check, you check if your vision is at all different from the norm; for example, if you have perfect vision without wearing glasses.

As well as doing this regularly, you could also do it every time you put on your glasses.

Examples of this reality check working

 * I'm in a room, and my vision is blurry because I'm not wearing glasses. I notice a sheet of paper with writing on it sitting on a table on the other side of the room. I try to read it, but it's too blurry. I look at it again and it comes into focus. A second later, I wonder how I can see it without glasses, but then realize I must be dreaming.
 * My vision disagrees with my other senses. Under my bare feet I can see a white carpet and feel a smooth wood floor. I decide that what I'm seeing is a dream, what I'm feeling is real, and therefore I must be sleepwalking. (I wasn't...hmm, is this a success or a failure?)
 * When I move, the scenery at the edges of my vision doesn't exactly flow by. It freezes and skips like a streaming video on a slow connection. I realize this is happening because the scenery isn't real - I'm dreaming it.

Examples of this reality check failing

 * I "wake up" from a dream, and get out of bed, but then I notice that I can see perfectly even though I don't have my glasses on. I figure my vision must have improved from resting and forget about it.
 * I was in front of my computer, with my glasses on, and everything was blurry. At first, I thought my vision had improved, so I removed my glasses, but then, I started thinking that if I could clearly see what was on the computer screen, without my glasses, that would mean I was dreaming. However, as soon as I looked at the screen, a black rectangle appeared just in front of it, and I could not see what was on the screen. I woke up.

Sueño lúcido/Test de Realidad/Visión

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Lucid Dreaming/Reality Checks/Vision


text:
Talk:Lucid Dreaming/Reality Checks/Vision

Also, check if your wearing your glasses, if you wear any. I've noticed that I have perfect vision in some dreams, which I can make super human. Rather fun. :D (anon)


text:
Guitar/Understanding the Strings

To properly understand the strings, the guitar must be in tune. The strings should be tuned to EADGBE. That is, the thickest string should be a low E, the next an A, and so on. This is called standard tuning. Other tunings exist, but we should not concern ourselves with them yet.

The fifth (standard A) and fourth (standard D) strings
The fifth string behaves similarly to the others: each fret is a single semitone up from the previous fret. The fifth fret on the fifth string is a D, which is the same note as the open fourth string. Likewise, the fifth fret on the fourth string is a G, the same as the open third string. This is the fret used to tune the string above it.

The third string
This string is slightly different from every other string on the guitar. The reason is the fourth fret on this string, not the fifth, has the same note as the second string.

The second string
The fifth fret is an E and the same as the open first string.

title: Guitar/Understanding the Strings


text:
Guitar/Harmonics

Harmonics are fun sounds to produce. They can be quiet and bell-like on an Acoustic or they can be loud and squeally on an overdriven Electric.

Harmonics Introduction
When you strike a note on the guitar, the sound generated is not just one note but a series of notes. The fundamental (also called the first harmonic) is the loudest and lowest of the series and fainter notes which all have their own frequency of vibration, amplitude, and phase are heard as well. The frequencies are integer multiples of the lowest frequency. Looking at the diagram you will notice that the upper partials (this is the name given to any sine waves associated with a complex tone) follow a pattern 2,3,4,5,6,and 7 and these equal-sized sections resonate at increasingly higher frequencies. The guitar technique described below shows how to play harmonics by lightly touching the string directly over the fret. You are essentially cancelling out certain partials from being heard by not allowing that part of the string to vibrate. Pianists have no means of manipulating strings to produce harmonics unless they lift up the lid of the piano and lightly touch the string. Woodwind instruments can produce harmonics by the technique of overblowing. It must be noted that we all tend to hear or play music as a "single sensation" and that the partials present are not considered or heard as separate during that experience.

List of natural harmonics

 * 12th fret - octave above open string
 * 7th or 19th fret - octave plus a perfect fifth above open string
 * 5th or 24th fret - two octaves above open string
 * 4th, 9th or 16th fret - two octaves plus a major third above open string

There are more harmonics than these but these are the easiest to produce and the most audible. They are ordered from lowest to highest in pitch.

Natural harmonics
Natural harmonics are the easiest to produce. A good place to begin is the 12th fret of the high e string. With your fretting hand, lightly touch a finger against the string directly above the 12th fret. Do not hold it down or apply any pressure. Then strike it with your picking hand and immediately release the string; almost simultaneously. If executed properly the result should be a high-pitched, silvery note. Try it again at the 7th and 5th frets; as shown on the Natural Harmonic fretboard diagram. Each harmonic shown on the diagram will produce a sound that is higher in pitch than its fretted note counterpart. Harmonics will sound quieter and the higher harmonics may be nearly inaudible without the overdrive of an amp.

Harmonic Chords
Below are the Harmonic chords of Em and Bm. Both chords are first inversion with the third in the bass. You can play Harmonic arpeggios, add the open low E string to the Harmonic Em chord or play a melodic phrase.

Below are the Harmonic chords of G and D. Both chords are second inversion with the fifth in the bass.

A good example of the use of natural harmonics is in the song Imperium by Machine Head. Clear 5th fret harmonics can be heard enforcing the low drop B tuning.

Pinch harmonics
Pinch harmonics are also known as Artificial Harmonics though there is really nothing artificial about them. This is an advanced technique and was popularized mostly by Billy Gibbons and later Zakk Wylde, as well as many others as early as the 1970s including many Heavy Metal artists. These harmonics follow the same principles of physics as a natural harmonic; the difference being how the harmonic is produced. In this technique a note is struck in a downwards motion with the pick and in the same motion the string is touched (one might really say brushed) with the edge of the thumb that is holding the pick. You can also use the edge of the index fingernail followed by the pick.

Pinch harmonics are most effective and audible using an Electric guitar with overdrive or distortion. These harmonics are virtually inaudible when using a clean (not distorted or overdriven) amp channel with the Electric guitar or when using an Acoustic. It can sound good when correctly used even without much overdrive but it's not always clear or detectable. Use overdrive or distortion for best results especially while learning and practicing this technique. This technique takes practice to master. Beginners may need to spend some time on scales, soloing, blues, riffing, strumming patterns before they feel comfortable enough to attempt this technique. It is mostly used in soloing and intense expressive riffing.

As mentioned above, these harmonics are produced by striking a note with the pick and touching the string with the picking thumb. Grip the pick so that the tip barely peeks out between your fingertips (this is why they are called "pinch" harmonics). It's easier when you are fretting a note with the left hand. Try fretting the 5th fret of the D string and plucking the string just below the neck pick-up pole pieces (maybe 1/8" toward the bridge from the pole pieces). The position of the plucking along the length of the string is one of the most important parts of this technique. While with regular picking the position of the picking along the string can make slight variations in the sound of the note, when executing pinch harmonics the right position is vital and tiny positional differences can make entirely different harmonics. So try adjusting the picking hand just millimeters up and down the string around the area of the pick-ups.

Try imagining the pick and your picking thumb plucking the string at the same time although the thumb is really just brushing past it. Consider it to be really one motion. Try thinking of your thumb and the pick as one entity and instead of picking straight down, pick down and a little bit (millimeters) out away from the face of the guitar so your picking motion is a sort of 'letter J' out from the face of the guitar and so the thumb brushes past the string and remember that the thumb should only touch the string for an instant just like the pick does.

Try executing pinch harmonics while fretting different notes and by striking the string in slightly different places all around the pickup area of the guitar. Many kinds of harmonic ringing sounds may be produced.

Without a pick, this technique may be simulated by plucking the string with the fingertip and lightly touching it with the fingernail. Classical guitarists use this technique and it is also found in jazz finger-style guitar.

These harmonics, as opposed to natural harmonics, end up being much more practical to use while playing and when mastered can be used boldly like Zakk Wylde making the harmonic part of the riff, or subtly and possibly unintentionally to add color and character to the notes or chords while playing almost anything.

Pinch harmonics can easily and effectively be combined with other techniques, such as bending or vibrato.

To hear pinch harmonics in action check out the following:
 * Ozzy Osbourne's Ozzmosis (and several other albums) features many different examples of pinched harmonics in various solos.
 * In the movie Rock Star at the beginning, the lead guitarist (Nick Catanese of Black Label Society/SPEED X) in Blood Pollution (the Steel Dragon cover band) is "not hitting the squeal". The squeal they're speaking of is a pinch harmonic.
 * One of the best examples of a bend and a pinch harmonic is Judas Priest's Lochness off the album Angel of Retribution at about 1:10.
 * In System of a Down's hit song BYOB it is the first bend in the chorus (Every bodys going to the party) part. It is the only PH in the song, so listen carefully

Don't despair if you can't get harmonics as clear as Judas Priest or Zakk Wylde, they've got equipment made just for making sounds like that. They both have expensive high gain amplifiers and their guitars are equipped with pickups that are naturally very good at pinch harmonics. Some pickups amplify pinch harmonics better than others (some pickups hardly amplify them at all). Judas Priest and Zakk Wylde both play guitars with EMG humbuckers, which are some of the hottest pickups and some of the best at amplifying pinch harmonics. Hot pickups (EMG, Duncan JB, Duncan Live Wire, Bill Lawrence 500XL) do an excellent job of picking up pinch harmonics. Once you've practiced at home, ask to try out a guitar with "hot pickups" and a "high gain" amplifier at the local guitar shop if you want a taste(warning: it's easy to get spoiled/hooked!).

Tapped harmonics
This technique, like tapping itself, was popularized by Eddie van Halen. Tapped harmonics are an extension of the tapping technique. The note is fretted as usual, but instead of striking the string, the string is tapped at one of the frets listed in the natural harmonic list. Do not hold the string down with the tapping hand, just bounce the finger lightly on and off the fret. This technique can be extended by fretting a note, then tapping relative to the fretted note. For instance, hold the third fret, and tap the fifteenth fret, for the twelfth fret harmonic, because 12+3=15.

Other techniques
A final technique (known as the harp harmonic) is a sort of combination between the natural and tapped harmonic techniques. Fret the note normally, and place the picking hand index finger on a natural harmonic relative to the fretted note (just as in tapped harmonics). Pluck the string with another finger and release the index finger, just as if producing a natural harmonic.

Chitarra/Armonici

title: Guitar/Harmonics


text:
User talk:Chrisbbehrens~enwikibooks

Welcome to Wikibooks, I am here to help you with anything you need should. Enjoy your work! --Karl Wick 22:51, 13 Apr 2004 (UTC)

Just when I got your email I think the Nasa site went down but I was able to read the image use policy page on the Google cache. Everything seems to be in order, the only phrase that could be a problem is: "It is unlawful to falsely claim copyright or other rights in NASA material." To know the full legal ramifications of that we might need a copyright lawyer but my opinion is that we are not claiming copyright on the images, falsely or otherwise, by including them in materials released under the GNU FDL. And IF it were to result in problems, we could just take the images out. If we use images from there just remember to attribute them to the source. - Karl Wick

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Chrisbbehrens. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Chrisbbehrens~enwikibooks that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:06, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 04:48, 19 April 2015 (UTC)

title: User talk:Chrisbbehrens~enwikibooks


text: Template:Investing

title: Template:Investing


text:
Investing/Mutual funds

Mutual funds come in a variety of different types. Fund managers select and group managed funds by industry sector (technology, international growth, etc.) as well as by risk level. A manager will buy and sell stocks within the area with the aim of getting the highest return on investment.

Mutual funds with potentially higher returns tend to be riskier, so an investor who needs to have his money back into his hands in three years will choose a less volatile fund so as not to risk losing the original investment. However, a person who is more prepared to lose money sometimes will likely gravitate towards the higher-return funds which will over the long term generate higher returns.

Index funds
An index fund is a mutual fund that holds a portfolio that seeks to match the performance of an index, for example the S&P 500. These funds have lower management costs than actively managed funds and therefore often outperform managed funds.

Exchange traded Funds
ETF's are simply Index funds which can be traded like stocks. They have the same advantages as the index fund with its low management fees. They are superior to index funds because trades can be placed at the same speed of a stock, versus the fund which cannot be purchased until the following morning.

Online resources
Many excellent resources available on the web:
 * About Mutual Funds
 * Morningstar
 * Mutual Funds 101 A 10-day Email Course
 * SmartMoney: Funds
 * Advantages and Examples of Using ETFs

title: Investing/Mutual funds


text:
Talk:Guide to Unix/Commands

Categorization
We need to categorize this list better. Perl 00:53, 14 Apr 2004 (UTC)~

 * Agreed. Additionally, it seems that this isn't a guide to the commands, so much as the output of appropos and a benign example.  Most entries don't include any switches.  Ironically, some of the few that do are typically invoked without switches.  As it stands this seems to be a general overview of essential unix commands for new users, but it is not very effective.  Granted it does list several commands which the new user might not be aware, but they would have to read the man page to fully understand the command and its usage.

 * --Eibwen 09:04, 25 Sep 2004 (UTC)

Crucial Commands Missing?
... Perhaps someone should glance at

 * UNIX Tutorial for Beginners by M.Stonebank http://www.ee.surrey.ac.uk/Teaching/Unix/
 * Unix Reference Guide http://webmonkey.wired.com/webmonkey/reference/unix_guide/

to make sure we haven't left out something crucial ...

chmod needs to be someplace--Wikiczar 22:39, 11 September 2005 (UTC)

 * I recently added chmod and chown to Guide to UNIX commands: File system utilities. --Kernigh 16:35, 8 October 2005 (UTC)

Proposed Restructuring
I propose renaming all of the Guide to UNIX commands pages to use the same slash syntax as pages that I recently added to Guide to UNIX. For example, Guide to UNIX commands: System Information would be renamed Guide to UNIX/Commands/System Information. I believe that this causes the wiki software to generate links up to Guide to UNIX and Guide to UNIX/Commands on each page. Naming conventions and Naming policy both suggest that the slash convention (or alternatively, the colon convention like Guide to UNIX:Commands:System Introduction ) be superior to the current colon-space system. Kernigh 23:40, 3 October 2005 (UTC)

 * Before you do that I suggest considering whether we want each command to have its own chapter (e.g. Guide to UNIX/Commands/ls). Uncle G 11:37, 11 October 2005 (UTC)

That would make them easier to link to. If we do that, then I want that the pages are significantly different from the ones at Wikipedia (like ls). I will try making an example page, but I have not time now, so I will post when it is ready. --Kernigh 00:20, 12 October 2005 (UTC)

User:Kernigh/chmod Example page (compare with chmod). I am not sure whether to split the current chapters (suggested by Uncle G) or keep the current chapters. --Kernigh 21:49, 12 October 2005 (UTC)

Also in the page names I want to capitalize the names. Getting Help and System Information are already capitalized, but I would move File system utilities to File System Utilities for example. (Unix command names like "ls" cannot be capitalized.) Also, the colon convention example is Guide to UNIX:Commands:System Information. --Kernigh 16:35, 8 October 2005 (UTC)

 * I personally prefer sentence case to title case. Uncle G 11:37, 11 October 2005 (UTC)

Most textbooks use title case, but GNU coreutils manual uses sentence case... --Kernigh 17:51, 15 October 2005 (UTC)

Categories from GNU Coreutils
The GNU coreutils manual at http://www.gnu.org/software/coreutils/manual/html_chapter/coreutils_toc.html contains 23 categories of commands. We have 15 categories in a different scheme. If Guide to UNIX commands changed to GNU's categorisation, we could merge material from their manual into ours, following the GFDL. (Our manual might not document all of the obscure options that GNU coreutils has.) (We would need a few extra cetegories, because some commands are not part of coreutils, and probably not all of them fit into the 23 categories.) This leaves five options for renaming the guide to slash convention: --Kernigh 17:51, 15 October 2005 (UTC)
 * Keep 1 page per category, and keep 15 current category pages
 * Keep 1 page per category, and switch to 23 GNU coreutils category pages
 * Split the pages to 1 page per command, and keep 15 current categories
 * Split the pages to 1 page per command, and switch to 23 GNU coreutils categories
 * Split the pages to 1 page per command, and have no categories

I would need to modify material I took from GNU coreutils, yet still credit them, so I've dropped it as an option. --Kernigh 20:18, 21 October 2005 (UTC) Advard

Death of a Template
I am moving it all to slash convention and uppercase titles now. It seems that Template:Guide to UNIX commandsTOC is leaving. I will insert it below to prevent is complete departure.

--Kernigh 21:10, 21 October 2005 (UTC)

if
Why there's no explanation of the if command, and its "scary" test options? Albmont (talk) 12:11, 9 September 2008 (UTC)

merge
Pretty much all the commands at Linux Guide/Linux commands are standard commands on any Unix-like system. Rather than maintain 2 copies of that information, I suggest we merge Linux Guide/Linux commands into Guide to Unix/Commands, leaving behind any Linux-specific commands and a link to "Guide to Unix/Commands". --DavidCary (talk) 16:50, 21 March 2009 (UTC)

 * This sounds reasonable, but we need to be careful as there is GNU, *BSD and other "Unices", some of who are, or claim to be, POSIX compliant. I don't know if it is essential to list only POSIX-compliant commands, or simply those that work on the most widely used Unix systems.  In principle, I welcome the merge.  If such a merge will occur I am planning to test the commands under OpenBSD, and change them if necessary (in that case I'll also test the updated commands on a GNU/Linux system). Hulten (discuss • contribs) 10:40, 1 February 2016 (UTC)

cron & at
missing these commands from this page see: https://en.wikipedia.org/wiki/Template:Unix_commands

title: Talk:Guide to Unix/Commands


text:
Guide to Unix/Linux

Linux® is an open source, Unix®-like kernel and operating system. The author of the kernel itself is Linus Torvalds, plus a loosely-knit team of programmers who enhance it in a collaborative effort over the Internet. This page provides a brief overview of the main features of the Linux kernel and system, especially in comparison to other Unix-like systems. There are several other Wikibooks about Linux with more information.

General Introduction

 * Distributions: The Linux system that you actually obtain, install, and run, is one of the many available Linux distributions. A Linux distribution (or 'distro' for short) is a bundle of the Linux kernel and applications and a suite of programs for installing and maintaining a Linux system.
 * There is much variation between distributions concerning the available packages, the installation procedure, the preferred desktop environment, and even the Linux kernel configuration. Some distributions have different target audiences: these might be home users, enterprise users, free software supporters, hobbyists, or users of certain applications.
 * Typically, distributions are in CD or DVD form. One can download them as a raw disc image in ISO format and burn it. One can also inexpensively purchase a Linux distro as a retail package. Live CDs or DVDs allow users to boot from a disc and run Linux using a RAM disk rather than a hard disk.
 * A Neutral Look at Operating Systems has a comparison of Linux systems.
 * Wikipedia has a list of Linux distributions.
 * Packages: A complete GNU/Linux operating system uses many free software (open source) packages from the BSD, X11, GNU, and other projects. There are also non-free packages without source code, or requiring one to buy licenses. Each distro decides which packages to provide.
 * Mascot: The official mascot of Linux is Tux, the Linux penguin.

Kernel

 * Copyright license: The Linux kernel and its source code are released under the GNU General Public License. Many of the userland packages also use this license. If you modify Linux or another package using this license, you can redistribute your modified version, but you must use the same license, which means you must provide source code. Every Linux vendor provides Linux source code.
 * Separate development: The Linux kernel is developed and maintained separately from userland.
 * With most other Unix-like systems, the kernel is maintained at least with the basic set of utilities, which would include the shell, shell utilities, C compiler, C library, system configuration utilities, and system boot scripts.
 * Linus Torvalds and his team can worry about the kernel (and userland programs which query and configure the kernel) and let other teams develop the userland system separately.
 * Both kernel and userland maintain extra compatibility so that one can update only the kernel, or only some userland package like the C library. In general, the Linux distro vendors take care of making updates install correctly.
 * Customizable kernel: Linux is probably the most customizable Unix-like kernel. There are even several ways to edit the kernel configuration before building the kernel.
 * Most builds of Linux use modules aggressively (though use of modules is optional). Modules allow pieces of the monolithic kernel, such as device drivers and network protocol implementations, to reside in separate files, load on demand, and unload when not used.
 * Many systems have multiple versions of Linux headers installed, in /usr/include/linux-version. Both the Linux kernel and some userland software, such as the C library, need these. On non-Linux systems, /usr/include/sys would sometimes have files used shared by the kernel and userland.
 * Special filesystems: Linux has some special filesystems which are not used for normal files.
 * /proc holds information about running processes. Other Unix-like systems sometimes provide /proc, but it is not as important as with Linux. Programs that use /proc often have trouble with ports to non-Linux systems.
 * /sys holds other information about the running kernel.
 * /dev is often a dynamic filesystem where device nodes appear and disappear dynamically, when modules load or unload or when devices are connected or disconnected. However, you can also just have /dev contain static device nodes like on other Unix-like systems.

Userland

 * GNU project: The GNU (GNU's Not Unix) project created the shell, core commands, C compiler and build tools for a Unix-like system. However, their kernel, Hurd, never worked well, and thus GNU encourages users to use Linux kernel.
 * Nearly every Linux distribution uses these programs, which makes them "GNU slash Linux" distributions. But with the exception of the GNU C library and core commands, many GNU tools and applications are also found on other Unix-like systems. In fact, *BSD and Mac OS X, like Linux, depend on the GNU C compiler, assembler, and linker.
 * The GNU project always insists on providing their packages as free software, using licenses like the GNU General Public License.
 * The GNU project also has a connection to the desktop environment called GNOME (GNU Network Object Model Environment).
 * /lib: The directory /lib exists on Linux and holds libraries needed by /bin and <tt>/sbin</tt> because <tt>/usr</tt> might not be mounted.
 * /usr: Stuff provided by your Linux distro often becomes installed in <tt>/usr</tt> instead of <tt>/usr/local</tt>. This frees <tt>/usr/local</tt> for packages which your Linux distro does not provide.
 * Text editors: Most distros provide the traditional Unix editors "vi" and "emacs", but some install neither by default. Even "ed" could be missing. Traditional Unix skills for text editing are not necessary when GNU "nano" is the installed non-X11 editor.
 * Package management: Most distros provide a package management system such as "apt" (Advanced Package Tool), "rpm" (Red Hat Package Manager), or Portage. These automate the installation and upgrade of packages. Both application packages and base system packages use this system. The package manager is often the biggest difference between distros.
 * Graphical user interface: Many of the popular Linux distros now boot the user straight into a desktop environment (GNOME or KDE, both based on X11 window system) immediately after installation. This is in contrast to some Linux distros and most *BSD distros which drop you at a root shell prompt, and expect you to use the root shell prompt to install X11, GNOME or KDE if you want it.
 * Source distros: Some Linux distros, such as Gentoo, emphasise building from source. Though every Linux distro with a compiler gives one the opportunity to rebuild the Linux kernel and other packages from source, these source distros provide scripts that not only automate the process, but help the system administrator make customisations and optimisations.

Linux Administration
Objective: To equip linux novice with essential administration skills to be proficient with the Linux environment.

cron

 * Definition: Cron is a scheduler that automatically executes a group of commands at certain time interval.
 * Configuration files:
 * 1. /etc/crontab - Main configuration
 * 2. /etc/cron.d/ - User based configuarton

Wikibooks for Linux
Wikibooks has several other books on its Linux section of the computing bookshelf. Here is a sample:
 * Linux Guide

In addition, some books have Linux chapters:
 * Computer Programming has information on Linux Programming
 * LPIC101 Certification: LPI Linux Certification/LPIC1 Exam 101/Linux Installation & Package Management
 * Movie Making Manual has information on Linux in film production

Distribution Related

 * Distro Watch
 * Linux ISOs

title: Guide to Unix/Linux


text:
Investing/Bonds

A bond is a debt: the issuer of a bond (a company, government, or other entity) borrows money from the purchaser of a bond (bond holder). Until the bond matures (the debt becomes due), the issuer will make periodic interest payments to the bond holder. On the maturity date of the bond, the issuer pays back the principal (the amount borrowed) to the bond holder, and possibly also makes a final interest payment.

From the point of view of the issuer, bonds may be an attractive alternative to borrowing from a bank (perhaps to avoid restrictive loan terms or to obtain a better interest rate), or to issuing stock (which would dilute the equity or ownership stake of the current owners of a company). From the point of view of the bond holder, bonds may be attractive relative to other investment alternatives, perhaps paying better interest rates than bank deposits or being more certain of retaining their value than stocks. With some exceptions, bonds are freely traded, so that the bond holders are not locked into their investments. (All of these advantages are possibilities and not certainties, as discussed below.)

As an illustration, suppose a company wants to build a factory which will cost US $1,000,000. The company may issue a bond to cover this amount. The bond could either be backed by the factory, or could be a debenture, which is only a call on the future income of the company. The face value of the bond would be $1,000,000, which typically would be sold in increments of $1,000. (The face value of the bond is distinct from the current price in the marketplace, which might be more or less than the face value.) The bond might pay an interest rate of 5% (also known as having a 5% coupon), typically in semiannual payments of 2.5% each, and could have a maturity of up to 30 years. For example, assuming the 5% and 30 year figures above, the bond typically would make 60 payments of $25 per $1000 of face value, with a final repayment of the principal coinciding with the last interest payment.

The purchase price of a bond is often not the price found on the bond itself, but can vary based on the interest rate of the bond, as well as the accrued interest on the bond. An increase in interest rates results in lower bond prices, and a decrease in interest rates results in higher bond prices (this is known as a loss or premium over the face value of the bond).

Bonds return around 5% a year on average. To have a higher return in bonds you invest in riskier bonds. They are known as junk bonds. Bonds have a credit rating which shows their risk rating. The credit ratings go from AAA, AA or A, BBB, BB B, CCC, CC, C, DDD, DD, D. AAA bonds are seen at a very low risk of default. BBB indicate some problems. CCC bonds can be viewed with caution. DDD are bonds at a high risk of default.

When can you use bonds? You could use bonds if you are an investor who would not want stocks and shares prices ups and down. How do you invest in bonds. You can invest in bonds through funds. You can also invest in bonds through stockbrokers. Be careful of too high charges on a bond fund, it could take away from the potential profits.

title: Investing/Bonds


text:
Electronics/History/Introduction

< ../../Expanded Edition/

Electronics has a long and varied history. It involves some of the most famous people in history.

title: Electronics/History/Introduction


text:
Electronics/History/Chapter 5

Space Age Tech

Fuel Cell
The first fuel cell was developed in the 19th century by British scientist Sir William Grove. A sketch was published in 1843. But fuel cells did not see practical application until the 1960s, where they were used in the U.S. space program to supply electricity and drinking water (hydrogen and oxygen being readily available from the spacecraft tanks). Extremely expensive materials were used and the fuel cells required very pure hydrogen and oxygen. Early fuel cells tended to require inconveniently high operating temperatures that were a problem in many applications.

Further technological advances in the 1980s and 1990s, like the use of Nafion as the electrolyte, and reductions in the quantity of expensive platinum catalyst required, have made the prospect of fuel cells in consumer applications such as automobiles more realistic.

Ballard Power Systems is a major manufacturer of fuel cells and leads the world in automotive fuel cell technology. Ford Motor Company and DaimlerChrysler are major investors in Ballard. As of 2003, the only major automobile companies pursuing internal development of fuel cells for automotive use are General Motors and Toyota; most others are customers of Ballard.

United Technologies (UTX) is a major manufacturer of large, stationary fuel cells used as co-generation power plants in hospitals and large office buildings. The company has also developed bus fleets that are powered by fuel cells.

title: Electronics/History/Chapter 5


text:
Electronics/History/Chapter 6

Computers

title: Electronics/History/Chapter 6


text:
Electronics/History/Chapter 2

Electricity and Magnetism: 1600-1875

Luigi Galvani
Luigi Galvani (September 9, 1737 - December 4, 1798) was an Italian physician and physicist who lived and died in Bologna.

Dissecting a frog at a table where he had been conducting experiments with static electricity, Galvani touched an exposed sciatic nerve of the frog with his metal scalpel, which had picked up a charge. At that moment, he saw the dead frog's leg kick as if in life. The observation made Galvani the first investigator to appreciate the relationship between electricity and animation--or life. He is typically credited with the discovery of biological electricity.

Galvani coined the term animal electricity to describe whatever it was that activated the muscles of his specimens. Along with contemporaries, he regarded their activation as being generated by an electrical fluid that is carried to the muscles by the nerves. The phenomenon was dubbed "galvanism," after Galvani, on the suggestion of his peer and sometime intellectual adversary Alessandro Volta.

Galvani's investigations led shortly to the invention of an early battery, but not by Galvani, who did not perceive electricity as separable from biology. Galvani saw electricity instead as the essence or the stuff itself of life, which he regarded vitalistically. Thus it was Volta who built the first battery, which became known therefore as a voltaic pile. While, as Galvani believed, all life is indeed electrical--in that all living things are made of cells and every cell has a cell potential--biological electricity has the same chemical underpinnings as the flow of current between electrochemical cells, and thus can be recapitulated in a way outside the body. Volta's intuition was correct as well.

Galvani's name also survives in the Galvanic cell, the galvanometer and "galvanize".

Alessandro Volta
Alessandro Giuseppe Antonio Anastasio Volta (February 18, 1745 - March 5, 1827) was an Italian physicist known especially for the development of the electric battery. Late in life, he received the title of Count.

De vi attractiva ... Volta was born and educated in Como, Italy, where he became professor of physics at the Royal School in 1774.

His passion had always been the study of electricity, and still a young student he had even written a poem in Latin on this fascinating new discovery.De vi attractiva ignis electrici ac phaenomenis inde pendentibus is his first scientific paper. In 1775 he devised the electrophorus, a device that produced a static electric charge. In 1776-77 he studied the chemistry of gases, discovered methane, and devised experiments such as the ignition of gases by an electric spark in a closed vessel.

In 1779 he became professor of physics at the University of Pavia, a chair he occupied for 25 years. In 1794 Volta married Teresa Peregrini, daughter of Count Ludovico Peregrini; the couple had three sons.

In 1800, as the result of a professional disagreement over the galvanic response advocated by Luigi Galvani, he developed the so-called voltaic pile, a forerunner of the electric battery, which produced a steady electric current. Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and silver. Initially he experimented with individual cells in series, each cell being a wine goblet filled with brine into which the two dissimilar electrodes were dipped. The electric pile replaced the goblets with cardboard soaked in brine. (The number of cells, and thus the voltage it could produce, was limited by the pressure, exerted by the upper cells, that would squeeze all of the brine out of the cardboard of the bottom cell.)

Templo Voltiano

In honor of his work in the field of electricity, Napoleon made him a count in 1810; in 1815 the Emperor of Austria named him a professor of philosophy at Padua.

Volta is buried in the city of Como in Italy; the Templo Voltiano near Lake Como is a museum devoted to explaining his work; his original instruments and papers are on display there. The building appeared, along with his portrait, on Italian currency before the introduction of the Euro.

An electrophorus is a simple plate capacitor used to collect static charge produced as a result of friction, devised in 18th century by Johannes Wilcke and Alessandro Volta.

The electrophorus consists of a dielectric plate on a metal surface and a metal plate with an insulating handle. First, the dielectric plate is triboelectrically charged, that is, by friction. Then, the metal plate is placed onto the dielectric plate. The metal plate charges by induction - the side facing the charged dielectric plate charges opposite to the charge of plate, while the side facing away from the dielectric charge attains the same sign of charge as the dielectric plate, thus making the metal plate electrically neutral as a whole. Then, the side facing away from the dielectric plate is momentarily grounded. Finally, the metal plate, now consisting only one sign of charge, is lifted.

The Voltaic Pile was invented by Alessandro Volta in 1800. He demonstrated that when certain metals and chemicals come into contact with each other they can produce an electrical current. He placed together several pairs of copper and zinc discs separated by paper soaked in salt water, and an electrical current was produced. This was the first chemical battery.

For his contributions to the study of electricity, the SI unit called the volt was named after Volta.

In 1881 an important electrical unit was named the volt was named in his honor.

Heinrich Hertz
Heinrich Rudolf Hertz (February 22, 1857 - January 1, 1894), was the German physicist for whom the hertz, the SI unit of frequency, is named. In 1888, he was the first to demonstrate the existence of electromagnetic radiation by building apparatus to produce radio waves.

Hertz was born in Hamburg, Germany, to a Jewish family that had converted to Christianity. His father was an advocate in Hamburg, his mother the daughter of a doctor. While at school, he showed an aptitude for sciences as well as languages, learning Arabic and Sanskrit. He studied sciences and engineering in the German cities of Dresden, Munich and Berlin. He was a student of Gustav R. Kirchhoff and Hermann von Helmholtz. He obtained his PhD in 1880, and remained a pupil of Helmholtz until 1883 when he took a post as a lecturer in theoretical physics at the University of Kiel. In 1885 he became a full professor at the University of Karlsruhe where he discovered electromagnetic waves.

Following Michelson's 1881 experiment (precursor to the 1887 Michelson-Morley experiment) which disproved the existence of Luminiferous aether he reformulated Maxwell's equations, to take the new discovery into account. Through experimentation, he proved that electric signals can travel through open air, as had been predicted by James Clerk Maxwell and Michael Faraday, and which is the basis for the invention of radio. He also discovered the photoelectric effect (which was later explained by Albert Einstein) when he noticed that a charged object loses its charge more readily when illuminated by ultraviolet light.

He died in Bonn, Germany.

His nephew Gustav Ludwig Hertz was a Nobel Prize winner, and Gustav's son Carl Hellmuth Hertz invented medical ultrasonography.

See also

People

* Wilhelm Röntgen * Hans Christian Ørsted * Guglielmo Marconi * Gustav Ludwig Hertz * Hermann von Helmholtz * James Clerk Maxwell * Nikola Tesla * Wilhelm Röntgen

Lists and histories

* Electromagnetism timeline * Timeline of mechanics and physics * List of physicists * Radio history * Wireless telegraphy * List of people on stamps of Germany * List of physics topics

Electromagnetic radiation

* Frequency o Hertz * Microwave * X-ray * Photoelectric effect * Radar * Luminiferous aether

Other

* University of Bonn * University of Karlsruhe * Radio

EM waves
The existence of electromagnetic waves, i.e. microwaves, was predicted by James Clerk Maxwell in 1864 from his famous Maxwell's equations. In 1888, Heinrich Hertz was the first to demonstrate the existence of electromagnetic waves by building apparatus to produce radio waves.

spectrum
It was Sir Isaac Newton in 1666 who first used the word spectrum to refer to the celebrated Phenomenon of Colours which can be extracted from sunlight, by a glass prism.

Infared
History In 1800 the English astronomer William Herschel held a mercury thermometer in the spectrum produced by a glass prism to measure the heat content of different coloured lights. He found that the thermometer registered an increase in temperature even when held beyond the red end of the spectrum, where there was no visible light. This was the first experiment to show that heat could be transmitted by an invisible form of light.

title: Electronics/History/Chapter 2


text:
Electronics/History/Chapter 1

Early days: < 1600

Baghdad Battery
The Baghdad Battery is an artifact from between 250 BC and 250, discovered near Baghdad, with a structure similar to that of a modern battery. It also appears that similar batteries can be located around ancient Egypt, where objects with traces of precious metal electroplating have been discovered at different locations.

In 1938, the German archaeologist Wilhelm Konig reportedly excavated the five-inch (13-cm)-long clay jar in Khujut Rabu, near Baghdad, Iraq (though some reports say it was found in the collections of the National Museum of Iraq). The jar contained a copper cylinder, in turn covering and protecting an iron rod, isolated from the copper by asphalt. The artifact had been exposed to the weather and had suffered corrosion.

Konig published paper reporting the mechanism's resemblance to a battery in 1940. Upon publication, Konig's discovery was discounted by the scientific community and soon disregarded. Such ancient knowledge in the history of electricity bears no known continuous relationship to the development of modern batteries. Its form, though, is nearly identical to the principles that are in use today. After the Second World War, Willard Gray demonstrated current production by a reconstruction of the inferred battery design when filled with substances, like grape juice. Subsequent tests found acidic residues in the original, analysed as an electrolytic solution, perhaps vinegar or wine.

Some people regard the Baghdad Battery as an anachronism (appearing to be out of place in time), because of the belief that ancient civilizations did not have electrical power and therefore would not have had a device that operated on the principles of electric power. The practical uses of this battery are uncertain. Some contemporary researchers have renewed interest in interpreting this artifact, and suggested electroplating precious metals as a practical use for early batteries by Baghdad Parthians (who used it to electroplate metallic items; e.g. put a thin layer of gold over an object made out of some other metal). Artifacts from ancient Egyptian sites, similarly resembling batteries, or bearing traces consistent with precious-metal electroplating, may support that.

Ark of the Covenant
Speculations that the Ark of the Covenant may have operated as an electrical capacitor are common amongst some electrical engineers (Nikola Tesla being the earliest); they say that the design of it allowed it to store electric charge, and thus could facilitate an electric discharge between the cherubs. The theory suggests that it resembles a capacitor (of radiant energy) in its construction. The biblical accounts of individuals sudden deaths from touching the Ark could correspond to death by a lethal high voltage charge. Louis Ginzberg’s "Legends of the Jews" has ancient oral traditions referring to "sparks" from the cherubim. These "fiery jets" occasionally burned and destroyed close objects. Other biblical accounts could correspond with exposure to some high frequency electromagnetic fields. Jewish legend has occasional records of a "cloud" between the cherubim. The Ark was considered dangerous at these times and Moses would not approach it.

Tesla, in the article "A fairy tale of electricity" (published September 9, 1915), stated in regards to the Ark:

 * "The records, though scanty, are of a nature to fill us with conviction that a few initiated, at least, had a deeper knowledge of amber phenomena. To mention one, Moses was undoubtedly a practical and skillful electrician far in advance of his time. The Bible describes precisely, and minutely, arrangements constituting a machine in which electricity was generated by friction of air against silk curtains, and stored in a box constructed like a condenser. It is very plausible to assume that the sons of Aaron were killed by a high-tension discharge, and that the vestal fires of the Romans were electrical." [2]

Archaeological discoveries of the last century (which include the Baghdad Battery among others), indicate that a working knowledge of energy devices might have been present in ancient Middle Eastern cultures, and therefore it might not have been beyond Moses' specialized training in the house of Pharaoh (Exodus 2:10).

It is known that the acacia wood acts as an insulator, while the gold (the purest available at that time) is known as a good conductor. An electric charge could have accumulated from constant exposure to static electricity in the Middle East climate (among other possible sources). The Ark's upper surface has a rim of gold (a single coil of angels figures). Over the ark, the cherubs could form a spark gap, producing a dynamic radiance that would inspire awe in the observer, and act as a lightning source to kill anyone that touched it.—Num. 7:9; 10:21; 4:5,19, 20; 1 Kings 8:3, 6; Lev. 16:2; Num. 7:89; 2 Sam. 6:6, 7.

Around 1999, author Richard Andrews built a model of the ark. He claims that when tested, it demonstrated that it would act as an electromagnetic accumulator.

title: Electronics/History/Chapter 1


text:
Guitar/Hammer-ons, Pull-offs, and Trills

Hammer-ons and pull-offs are two closely related techniques. They are used to play legato, that is, in a smooth manner, and are also used to help the guitarist to play faster. They are most commonly used in electric guitar work, but can be used in acoustic tunes as embellishments.

The hammer-on
Hammer-ons can be done anywhere on the fretboard, but for the beginner it is easiest using an open string. To quickly learn, strike an open E on the first string. While the note is still ringing, quickly and firmly press a finger on the third fret. If done properly, a G note should be sounding.

Quickly pressing your finger down and raising the note without hitting the string again is called "hammering on". Without electric amplification, the hammer-on tends to be quieter than regularly struck notes, especially if you haven't practiced it! Because the strings are closer to the fretboard, hammer-ons are easier to execute on an electric guitar. However, this doesn't make them less common on an acoustic guitar, where they are used frequently to embellish open chords

The hammer-on can just as easily be played with fretted notes: just play the note normally and hammer onto another (higher-numbered) fret on the same string. If you practice hammer-ons, eventually you will be able to move each finger smoothly and independently.

The pull-off
The pull-off is the opposite of the hammer-on. Again, using the E string, hold it at the third fret. Strike the string and while the note is still ringing, release the fretting finger. If done properly, the G should be followed by an open E. If the note doesn't ring out properly, try hitting the G harder and releasing faster.

Like the hammer-on, the second note tends to be less loud than the first. To help alleviate this, a slight sideways motion of the fretting finger while pulling off will add extra vibration to the string, and give you some extra volume. Often it is hard for a beginner to accomplish, and the sideways movement helps greatly.

A pull-off looks like this: D|---7p5--5p4--4p2--2p0--|

The trill
A trill is two alternating notes, such as an A and A#. Only the first note is struck; the rest are rapidly hammered-on and pulled off

de:Gitarre: Folkdiplom - Hammer-On Chitarra/Hammer on e Pull off