user

USER
Seperti yang telahkitaketahui, Linux termasuksistem multiuser dimanasuatu resource bisadigunakanolehbanyak user. Setiap user biasanyadiberiruangan yang disimpanrapidalamdirektori /home. Setiap user, pada home masing-masingmemilikihakmengakses, membacaataumenulis file-file di dalam home merekasendiritetapimerekabelumtentubisamelakukanhal yang sama di home milik user lain ataudirektorimilik root. Masing-masing user bisadiberihak-hakkhusus yang berlainanuntukmengakses, membacaataumenuliskesebuah file ataudirektorioleh root. Olehkarenaitukitabisasajameninggalkan root sepanjangharidengancaramembuat home sendiri, login sebagai user biasasertamemberikanhakaksesseperlunyasaja agar tidakmembahayakansistembilasuatusaatkitamelakukankesalahan.

Untukmenambahkan user di linuxdapatdilakukandenganperintah adduser atauuseradd. Tetapiterdapatperbedaanpadakeduaperintahtersebut, yaitu:

adduser :
1. Menciptakan user denganmelakukan setting password.
2. Menciptakan user beserta home direktorinya.
3. Menciptakan user denganmemberikanketeranganlengkap user tersebut.

useradd :
1. Menciptakan user tanpamelakukan setting password.
2. Menciptakan user tanpaada home direktorinya.
3. Menciptakan user tanpamemberikanketeranganlengkap user tersebut.

Contoh :

• Adduser dan useradd

 

Anda jugadapatmengubah password user denganmengetikkanperintah passwd [nama user] danbisajugamenghapus user yang tidakdiinginkandenganmengetikkanperintahuserdel [nama user]. Keduaperintahtersebutdapat di eksekusi di terminal.

GROUP

Setiap user dapatbergabungkesebuah group. Group bisaberisikumpulan user lain atau program yang mempunyaikesamaantugas. Group memungkinkansebuah file bisadipergunakansecarabersamahanyaoleh user-user yang tergabungdidalam group tersebut. Olehkarenaitucaramengelompokkan user-user dalam group iniadalahsalahsatucara yang mudahbagi root untukmemberikanhakakses file-file miliknyakepadasekelompok user.

Untukmembuatsebuah group baru, Andabisamenggunakanperintah groupadd. Misalnya, Andainginmembuat group barudengannama goprasnia makaperintah yang harusdiketik di terminal adalah groupaddgoprasnia. Anda jugadapatmengubah password group denganmengetikkanperintah gpasswd [nama group] danbisajugamenghapus group yang tidakdiinginkandenganmengetikkanperintah groupdel [nama group]. Keduaperintahtersebutdapat di eksekusi di terminal.

Berikutnyaadalahmenambahkan user yang akanbergabungkedalam group goprasniaini. Informasi group disimpandalam file /etc/group, bukalahdenganmenggunakan editor kesayanganAnda. Kemudiantambahkannama-nama user yang akanbergabungdalam group

Setiapbarisdalam file /etc/group terdiridariempatsegmen yang dipisahkanolehtandatitikdua (:)

nama group : password : group id (gid) : user

Carilahbaris group goprasnia dancukuptambahkannama user yang akanbergabungdengan group goprasnia ini di segmenterakhir. Pisahkannama user dengantandakoma (,) bila user yang bergabunglebihdarisatu

Password biasanyakosongatau * ataubiarkansajabilaAndatidakmembuat password untuk group ini. Setelah file /etc/group ini di simpanmakatugasberikutnyaadalahmerubah permission dan ownership file-file yang bisadiaksesoleh group goprasnia.

PERMISSION

• Chown

Merubah user ID (owner) sebuah file ataudirektori.
Contohperintah :
chown [nama user] [file yang akan di edit kepemilikannya]

• Chmod

Digunakanuntukmenambahdanmengurangiijinpemakaiuntukmengaksessebuah file ataudirektori. Andadapatmenggunakansistem numeric coding atausistem letter coding. Ada tigajenis permission yang dapatdirubahyaitu r (read), w (write) dan x (execute).

Denganmenggunakan letter coding, Andadapatmerubah permission diatasuntukmasing-masing u (user), g (group), o (other) dan a (all) denganhanyamemberitanda plus (+) untukmenambahijindantanda minus (-) untukmencabutijin.

 

PERINTAH DASAR LINUX , MANAJEMEN USER,GROUP DAN FILE

1. Sudo su diigunakan untuk login sebagai root/pengguna tertinggi

2. Login diigunakan untuk login sebagai user lain, namun harus menjadi root dulu untuk bisa menjalankan perintah ini.

3. date digunakan untuk melihat tanggal sekarang, cal untuk melihat kalender

4. Hostname digunakan untuk melihat hostname, uname –a menampilkan semua informasi, uname –m untuk menampilkan tipe hardware

5. Who untuk mencetak semua pengguna yang sedang login, whoami untuk mencetak pengguna saat ini dan nama ID

6. PWD digunakan untuk memperlihatkan di direktori mana posisi kita berada sekarang.

7. Menampilkan bantuan untuk beberapa perintah contohnya perintah ls

8. Clear untuk membersihkan perintah-perintah yang diketikan sebelumnya

9. Mengetahui perintah-perintah apa saja dilihat dari fungsinya secara massal

10. Mendapatkan informasi dari perintah secara singkat (dibawah ini informasi singkat dari date)

11. Perintah ini berfungsi untuk menampilkan isi dari suatu directory beserta atribut filenya.

12. touch digunakan untuk membuat file baru.

13. mkdir digunakan membuat sebuah directory atau folder.

14. cd digunakan untuk berpindah direktori.

15. cp digunakan untuk melakukan copy file.

16. mv digunakan untuk melakukan memindahkan, cut atau rename file.

17. rm digunakan untuk menghapus file.

18. more digunakan untuk menampilkan isi sebuah file

19. cat untuk membuat file tertentu dan mengisinya

20. Mail berfungsi mengirimkan mail ke diri sendiri (G1 gambar mail belum terinstall, G2 adalah gambar mail sudah terinstall dan terkirim)

21. cut berfungsi mendefinisikan suatu file yang berisi data berdasarkan kolom

22. Find untuk mencari file atau directory

23. Grep untuk mencari data dalam file tertentu.

24. Kegunaan perintah in adalah untuk membuat link dari satu file/directori ke file/directori lain.

25. Perintah locate digunakan untuk mengetahui dimana letaknya sebuah file atau directori. Fungsinya kurang lebih sama dengan find, bedanya locate menggunakan sebuah database (biasanya terletak di /var/lib/locatedb ) yang dapat di update menggunakan perintah updatedb.

26. dir memiliki fungsi yang sama dengan perintah ls, yaitu menampilkan is direktori. Anda bisa membuka manual dari perintah dir. Pemberian option dan argument sama dengan perintah ls.

27. Perintah ini berlawanan dengan perintah cut, tail mendefinisikan sebuah data pada file menurut barisnya. Sedikit perbedaan adalah pada tail secara default ditampilkan 10 baris terakhir dari isi file

28. wc adalah perintah untuk menampilkan jumlah baris, jumlah kata dan ukuran dari sebuah file. (Terdapat 2 baris, 5 kata, dan 18 karakter pada file tes)

29. sort untuk mengurutkan isi file berdasarkan huruf

30. logout digunakan untuk logout dari system.

31. history digunakan melihat perintah yang telah dihentikan

32. Reboot untuk merestart ubuntu, dan shutdown untuk mematikan ubuntu (harus masuk sudo su terlebih dahulu)

33. Perintah sudo su digunakan jika ingin berpindah dari user biasa ($) menjadi super user atau root (#)

How Cookies Work

Cookies and other similar technologies help provide a better, faster and safer experience.

Technologies like cookies, pixel tags (“pixels”), and local storage are used to deliver, secure, and understand products, services, and ads, on and off Facebook. We want this page to help you understand more about these technologies and how they are used. Your browser or device may allow you to block these technologies, but you may not be able to use some features on Facebook if you block them. For more information about whether these tools are available, what they do and how they work, visit your browser or device’s help material. Generally, tools like these in your browser or device affect only that particular browser or device. So if you’re using multiple browsers or devices, you can make different choices for each of them.

What are cookies, pixels, local storage and similar technologies?

We and our affiliates, third parties, and other partners (“partners”) use these technologies for security purposes and to deliver products, services and advertisements, as well as to understand how these products, services and advertisements are used. With these technologies, a website or application can store information on your browser or device and later read that information back. We explain more about each of these technologies and how they are used on this page.

Original Chip Made in Indonesia ?!.,,,,

Xirka Wimax chipset, a chip made ​​by an Indonesian native, not an easy effort is made ​​chips with a fairly high complexity. Xirka Indonesian engineer who escorted some of these were developed in 2006. This chipset consists of two specifications, namely Chipset Xirka for Fixed Wimax and Mobile Wimax Chipset Xirka for. For fixed wimax was launched in August this year. While mobile wimax slated for release in the fourth quartal 2009.Produk original made in Indonesia was launched by the Minister of Research and Technology of the Republic of Indonesia, Kusmayanto Kadiman. He explained that all the components in the Xirka is made ​​in Indonesia. Wimax operators who provide services must use Xirka.

The Role of Memory in Computer Processing of Data

Computer memory speeds up the processing of data by the central processing unit, or CPU. Memory is accessed much faster than a physical storage device, such as a hard drive. By placing certain data in memory, the computer can access the data quicker, which allows its overall functioning to be more efficient.

Functions of Computer Memory

• Computers store data and sets of instructions in memory for quick access. The operating system’s core files are stored in the memory so the computer is functional for the user. As processes are executed, needed information is stored in the memory so that the CPU can quickly navigate between the data that it needs. This prevents the CPU from needing to access the hard drive for everything.

Multi-Tasking

• Multi-tasking uses memory to allow a user to run multiple programs at once. Different programs are stored so they can be switched between seamlessly. This enhances the user’s productivity.

Raw Speed

• Memory access speeds are thousands of times faster than hard drive access speeds. A hard drive is a mechanical device with moving parts. It can only find and use data at a certain rate. Memory is lightning fast in accessing what it holds. This makes using your computer much more efficient and pleasant.

How Computers Work ?

The computer does its primary work in a part of the machine we cannot see, a control center that converts data input to information output. This control center, called the central processing unit (CPU), is a highly complex, extensive set of electronic circuitry that executes stored program instructions. All computers, large and small, must have a central processing unit. As Figure 1 shows, the central processing unit consists of two parts: The control unit and the arithmetic/logic unit. Each part has a specific function.

Before we discuss the control unit and the arithmetic/logic unit in detail, we need to consider data storage and its relationship to the central processing unit. Computers use two types of storage: Primary storage and secondary storage. The CPU interacts closely with primary storage, or main memory, referring to it for both instructions and data. For this reason this part of the reading will discuss memory in the context of the central processing unit. Technically, however, memory is not part of the CPU. 

Recall that a computer’s memory holds data only temporarily, at the time the computer is executing a program. Secondary storage holds permanent or semi-permanent data on some external magnetic or optical medium. The diskettes and CD-ROM disks that you have seen with personal computers are secondary storage devices, as are hard disks. Since the physical attributes of secondary storage devices determine the way data is organized on them, we will discuss secondary storage and data organization together in another part of our on-line readings. 
Now let us consider the components of the central processing unit.

Windows 9 True or False ?

 

Microsoft officially unveiled Windows 8 in October 2012. But the rumors have accompanied the operating system’s successor.

Previously widely heard if Microsoft is preparing the first update of Windows 8, the Windows named Blue. But is it just?

Of course not, because the sources are obtained by Digitimes claims that the software giant is currently preparing another generation of Windows.

Rumors circulating mentioning that this is referred to as Windows 9. It would be the latest generation after Windows 8. from Softpedia, Tuesday (09/04/2013).
The source also get leaked that Windows 9 is the middle of the work period will be launched shortly after Windows Blue presented. That is, if the Windows Blue crowded reported released around August, then Windows 9 will be in October. Fitting a year after the birth of Windows 8

DIGITS HAND TRACKER

The new microsoft digits, which was recently unveiled at a technology conference, allows for freehand 3-d interaction by wearing a gloveless sensor on the wrist. The integrated technology remembers and recovers certain poses of the user’s hand, and since the sensor is only on the wrist, the user is free to interact freely with other devices. It can be used to play video games or as a virtual tv control and can even operate a smartphone without leaving the user’s pocket.

This tool is similar to a wristwatch, so you just wear it .. after that you can directly control a computer with hand gestures.

 

 

Sensoring Technology

 

The secret to the Digits success lies in its understanding of how the human hand moves. By being able to copy every movement from the orientation of the wrist to the angle of each joint of the finger, its 3d functionality is not tied down to any point in space. Similar products in the past have relied on the user wearing a special sensoring glove, but that is not necessary with the Microsoft prototype, which delivers the same accuracy but with more flexibility.

 

Added Mobility

 

One of the main goals of the Digits team was to provide superior mobility. Since the Digits sensor is worn on the wrist and does not use an external infrastructure, users are not restricted to movement within a fixed space. It is small, comfortable, lightweight and needs a minimum amount of power. With its built-in technology, the 3D interaction follows the user around indoors or out.

 

Integrated Components

 

The beauty of Digits is that it is built entirely of cheap products easily found on the open market. The basis of the system is a simple infrared camera with a laser line generator and goes on to add an infrared diffuse illuminator and an inertial measurement unit. The components integrate beautifully to interpret data and construct a fully articulated model of the hand.

Digital Image File Types Explained

JPG, GIF, TIFF, PNG, BMP. What are they, and how do you choose? These and many other file types are used to encode digital images. The choices are simpler than you might think.

Part of the reason for the plethora of file types is the need for compression. Image files can be quite large, and larger file types mean more disk usage and slower downloads. Compression is a term used to describe ways of cutting the size of the file. Compression schemes can by lossy or lossless.

Another reason for the many file types is that images differ in the number of colors they contain. If an image has few colors, a file type can be designed to exploit this as a way of reducing file size.

Lossy vs. Lossless compression

You will often hear the terms “lossy” and “lossless” compression. A lossless compression algorithm discards no information. It looks for more efficient ways to represent an image, while making no compromises in accuracy. In contrast, lossy algorithms accept some degradation in the image in order to achieve smaller file size.

A lossless algorithm might, for example, look for a recurring pattern in the file, and replace each occurrence with a short abbreviation, thereby cutting the file size. In contrast, a lossy algorithm might store color information at a lower resolution than the image itself, since the eye is not so sensitive to changes in color of a small distance.

Number of colors

Images start with differing numbers of colors in them. The simplest images may contain only two colors, such as black and white, and will need only 1 bit to represent each pixel. Many early PC video cards would support only 16 fixed colors. Later cards would display 256 simultaneously, any of which could be chosen from a pool of 2²⁴, or 16 million colors. New cards devote 24 bits to each pixel, and are therefore capable of displaying 2²⁴, or 16 million colors without restriction. A few display even more. Since the eye has trouble distinguishing between similar colors, 24 bit or 16 million colors is often called TrueColor.

The file types

TIFF is, in principle, a very flexible format that can be lossless or lossy. The details of the image storage algorithm are included as part of the file. In practice, TIFF is used almost exclusively as a lossless image storage format that uses no compression at all. Most graphics programs that use TIFF do not compression. Consequently, file sizes are quite big. (Sometimes a lossless compression algorithm called LZW is used, but it is not universally supported.)

PNG is also a lossless storage format. However, in contrast with common TIFF usage, it looks for patterns in the image that it can use to compress file size. The compression is exactly reversible, so the image is recovered exactly.

GIF creates a table of up to 256 colors from a pool of 16 million. If the image has fewer than 256 colors, GIF can render the image exactly. When the image contains many colors, software that creates the GIF uses any of several algorithms to approximate the colors in the image with the limited palette of 256 colors available. Better algorithms search the image to find an optimum set of 256 colors. Sometimes GIF uses the nearest color to represent each pixel, and sometimes it uses “error diffusion” to adjust the color of nearby pixels to correct for the error in each pixel.

GIF achieves compression in two ways. First, it reduces the number of colors of color-rich images, thereby reducing the number of bits needed per pixel, as just described. Second, it replaces commonly occurring patterns (especially large areas of uniform color) with a short abbreviation: instead of storing “white, white, white, white, white,” it stores “5 white.”

Thus, GIF is “lossless” only for images with 256 colors or less. For a rich, true color image, GIF may “lose” 99.998% of the colors.

JPG is optimized for photographs and similar continuous tone images that contain many, many colors. It can achieve astounding compression ratios even while maintaining very high image quality. GIF compression is unkind to such images. JPG works by analyzing images and discarding kinds of information that the eye is least likely to notice. It stores information as 24 bit color. Important: the degree of compression of JPG is adjustable. At moderate compression levels of photographic images, it is very difficult for the eye to discern any difference from the original, even at extreme magnification. Compression factors of more than 20 are often quite acceptable. Better graphics programs, such as Paint Shop Pro and Photoshop, allow you to view the image quality and file size as a function of compression level, so that you can conveniently choose the balance between quality and file size.

RAW is an image output option available on some digital cameras. Though lossless, it is a factor of three of four smaller than TIFF files of the same image. The disadvantage is that there is a different RAW format for each manufacturer, and so you may have to use the manufacturer’s software to view the images. (Some graphics applications can read some manufacturer’s RAW formats.)

BMP is an uncompressed proprietary format invented by Microsoft. There is really no reason to ever use this format.

PSD, PSP, etc. , are proprietary formats used by graphics programs. Photoshop’s files have the PSD extension, while Paint Shop Pro files use PSP. These are the preferred working formats as you edit images in the software, because only the proprietary formats retain all the editing power of the programs. These packages use layers, for example, to build complex images, and layer information may be lost in the nonproprietary formats such as TIFF and JPG. However, be sure to save your end result as a standard TIFF or JPG, or you may not be able to view it in a few years when your software has changed.

Currently, GIF and JPG are the formats used for nearly all web images. PNG is supported by most of the latest generation browsers. TIFF is not widely supported by web browsers, and should be avoided for web use. PNG does everything GIF does, and better, so expect to see PNG replace GIF in the future. PNG will not replace JPG, since JPG is capable of much greater compression of photographic images, even when set for quite minimal loss of quality.

File size comparisons

The classification of information technology

Continue my last article “ What is information Technology (IT) ? ” From this  we know that Information Tachnology cover computer Technology and Communication Technology . Detailed,  Information Technology have 5 type are input technology, processing machine technology,storage technology,output technology and software technology.

1. Input Technology
   Input technology is a technology that have relation with something to input data in computer sistem. Input tool usually found in computer sistem form keyboard and mouse.
2. Processing machine technology
   Processing machine called CPU(Central Processing Unit), mikroprosesor, or  prosesor. For example a famous processor now on are Pentium and Power PC.
3. Storage Technology
   Storage technology differ to  2 group,there are internal and external memory.Internal memory called main memory use to temporary saver for data, program, or  information when processing by CPU.example to internal memory are ROM and RAM. In  ROM (Read Only Memory) we just can read data,we can’t upgrade or change data but in RAM we can do it.external storage called secondary storage.External storage is permanently data saver, our data still save save without electricity power.example : Harddisk ,disket and Flashdisk.
4. Output technology
   Output technology is a technology that relation with output sistem.example of output technology are  Monitor and printer  .
5. Software Technology
   Software called program. Of course to doing  computer function, needed software self. For example : Microsoft Word is software to processing the word and making some document, Adobe Photoshop to processing a picture.

Hopefully, this article can provide greater insight and to contribute ideas to the readers especially the students of Brawijaya University. We are aware that this paper is still a lot of flaws and is far from perfect. Therefore, to our English lecturer asks input for improving our article  making in the future and expect criticism and suggestions from readers.

Andrika Wahyu W – 125150300111037