Advantages of using a shell

Greater control
A shell is a program that acts as an interface between the user and the operating system, just as a GUI does. However, a shell works without graphics – when you use one, you issue instructions to the operating system by typing in commands. In fact, the shell is often referred to as a command interpreter.

This may seem like a return to basic computing, but a command-line interface lets you exercise a degree of control over the operating system that would otherwise be lacking. There are a number of reasons for this:

• with a GUI, only the options provided by the interface are available to the user
• lack of space on a screen can limit the number of options that a GUI displays
• no standard methods exist within GUIs for performing standard command-line tasks, such as linking commands in sequences, redirecting output from one destination to another, or collecting commands into scripts

A disadvantage of using a command-line interface is that the user needs to learn a wide variety of sometimes cryptic commands and their associated options. However, the commands are more powerful and adaptable than their GUI counterparts, because they can be extended and fine-tuned through the use of options. An expert user of a command-line interface can issue complex commands very quickly. Techniques also exist to link multiple commands together with pipes and redirections, so that the output of one command becomes the input of another. Linux can interpret commands issued using the shell more quickly than GUI commands. This is because shell commands are nothing more than simple ASCII text. Some shells even enable you to define your own commands.

Automation of common tasks
A shell has another advantage over a GUI in that it keeps a history list of recently issued commands. This enables a user to step back and forth through this list, reusing commands at any point. In addition, a shell enables you to string commands together to form a shell script. These scripts work in a similar way to batch files, issuing multiple commands as one. You can use them to automate common tasks that would otherwise require you to issue several, consecutive commands.

Speed and efficiency
In hardware terms, a shell is a more attractive proposition than a GUI. Shells are much less resource-intensive than GUIs – they require less memory, for example. This means that a command issued in the shell will run more quickly and efficiently than the same command run in a GUI. It also means that a shell supports Linux’s multitasking environment, in which multiple tasks run simultaneously, more comfortably than a GUI, in which the GUI itself competes for CPU resources.

Shell evolution

Since its creation as a derivative of UNIX, Linux has given rise to a number of shells, which have evolved along with the operating system itself. When a new shell is developed, it doesn’t spell the end for all previous shells. Many different Linux shells are available, and each has particular strengths. The one you use depends on your own preferences and on the task you wish to undertake.

The default shell in most Linux installations is the Bourne Again shell, or /bin/bash. It is a successor to the Bourne shell, or /bin/sh, which was an early and less powerful Linux shell. The Bourne Again shell was created and is distributed by the Free Software Foundation. It offers features such as command-line editing and filename completion. It is an ideal first shell for Linux newcomers. In addition, bash supports the syntax used by another Linux shell called the C shell, or /bin/csh, which increases its flexibility.

You can find out which shell you’re running at any time by typing the command echo $SHELL at the shell prompt. The default shell is specified in the /etc/passwd file and can be changed there for each user.

Since we are talking about Linux here, you might want to know how to mount linux file system also understand on Linux File Types.

According to the vendor ,the Original Cisco Console Cable worth approximate RM100 above (60USD++). Usually Cisco console cable only come with each Cisco product you bought, but I found that ebay just sold at around 5USD to 10USD exclude shipping fees, while local website sold at RM60 above.

Should be those user who bough a lot Cisco switches and router, and they only use few to configure their Cisco device.

I was thinking does any Cisco’s Freak out there custom DIY their own Cisco Console Cable? I guess I am one of the “freak” who plan to do it.

Before I get start to DIY Cisco Console Cable, I require to know the arrangement of the cable. Arrangement on the RJ45 pin and another end at DB9 port.

Let study on the serial port numbering location 1st (DB9),  and RJ45 numbering location 1st. below are the port number for DB9 connector and RJ45 port number:

DB 9 Port Pin Number

RJ45 Pin Number

The color code for Cisco Console Cable as below:

rj45-1 to db9-8

rj45-2 to db9-6

rj45-3  to  db9-2

rj45-4 to db9-5

rj45-5 to db9-5

rj45-6 to db9-3

rj45-7 to db9-4

rj45-8 to db9-7

To confirm the above Cisco Console Cable color code correct, I require to do some verification. I require a Multimeter, mostly I will prefer tone mode, which mean the positive (Red) and negative (Black) touch together, will hv beep sound from the multimeter.

I require a  mini gender changer, male to male type, shown as below:

I connected this mini gender changer to the Cisco Console Cable’s Serial Port end as shown the picture below:

I need to use either 1 end of the multimeter to point to the RJ45’s Pin 1, and another end touching each pin on the DB9 serial connector until the beep tone occur. Record down which pin is come from RJ45’s Pin 1 (as above stated, RJ45’s Pin 1 connected to Db9’s Pin

Repeat the same step for RJ45’s Pin 2 until Pin 8, the result will be as above Cisco console cable color code.

After get known all the color code, now you require to get a soldering iron, and also a female db9 connector.

Solder the RJ45 cable to the DB9 Connector according to the cisco console cable color code above

You can get variety of db9 connector which come with cover, just like as below. I does not know what this kind of connector call, but it is very convenience just to have 1 pcs of this DB9 to RJ45 connector.

If you interested to DIY your own Cisco Console Cable, you can have a try, the above Cisco Colsole Cable color code has been proven correct by me. To ensure all the thing goes smoothly, it is advice to test it your self before you create your own console cable.

Happy “Do it Your Self” Cisco Console Cable.

It is an important part of the role of the Linux system administrator to ensure that file systems are mounted correctly, whether at boot time or manually, to ensure that all required data is available at the expected locations.

Advantages of mounting Linux file systems and devices

Devices are mounted at predetermined directories below the root file system. These are usually, although not always, special directories created for the purpose. The file systems that belong under the /var, /home, and /usr directories, for example, are kept on separate partitions or devices from the root file system. Network machines are frequently configured so that the /home data for all machines is actually stored on a single Network File System (NFS) server, which is then mounted under the /home directory on each individual machine. This enables users to access their own home directories in the usual locations, regardless of which computers they are actually logged on at.

Because all devices and file systems appear below the root directory, the transition from one device or file system to another is entirely seamless. So a user can access a file on an NFS server over a network as though the file were on the local hard drive.

Linux makes it easy to expand the space available to overloaded file systems by mounting new partitions. For example, say the directory /home/project is filling up with so much data that it threatens to take over the hard drive on which it is stored. The system administrator can easily move the data from the existing /home/project to an empty disk partition with more available space, and remount the new partition at /home/project. To users, there won’t be a difference between the old configuration and the new one – they still access their files under /home/project, even though the files are now stored on a completely different hard drive.

It is important to mount file systems in the correct order. This is sometimes necessary to ensure that the mount point required by a given file system exists and is available when the mount command is issued. Taking the /home/project example again, the project data exists on one disk partition and all the remaining /home data is on another, including the /home/project directory under which the /home/project partition is to be mounted. Clearly, if an attempt is made to mount the /home/project partition before the /home partition, this will result in an error, as the /home/project directory doesn’t yet exist. The correct order is to mount the /home partition first, followed by the /home/project partition.

It is also important to be aware when mounting devices under a given directory that any files previously available under that directory will be hidden while the device is mounted. So any files that still remain in the /home/project directory of the /home partition will become invisible as soon as the /home/project partition is mounted in that directory. Furthermore, the disk space those files occupy will remain unavailable to the system until the project partition is unmounted. You should therefore check what already exists in a directory before you use it as the mount point for some other file system, to avoid duplicating files or wasting disk space.

File system mounting management

To assist in the management of file system mounting, a special directory called /mnt exists in most Linux distributions. This directory contains dedicated directories for mounting specific devices such as CD-ROM, floppy disk, and zip disk drives. This is a convenient way to ensure that such devices have a suitable mount point available to them at all times.

Removable media

It is impossible to access the data on removable media without mounting them first. To use a floppy disk drive, for example, you need to issue the mount command before the disk contents will be visible to the system.

Similarly, when you have finished using any kind of removable medium, it is very important to unmount the device using the umount command before removing the disk from the drive. This is because Linux improves efficiency by often storing information in memory buffers rather than writing it directly to the disk. If a removable disk is removed without being unmounted first, there is a high probability of data loss, just as there is from a hard drive if you shut down the system by turning off the power without running the proper shutdown procedure.

Trend always change time by time; long time ago when Digital Camera introduce to the world, the size are consider big, with using Compact Flash (CF) card and Smart Media card (SM); as time goes by, the size design to become smaller, and using Secure Digital Card (SD). Again, within this few years, Digital Single Lens Reflect (DSLR) camera has became cheaper and cheaper, and most of the people afford to own it.

as people said

Throw a stone to a group of people, sure will hit 1 Degree holder

as iCalvyn said

Throw a stone to a group of people, sure will hit 1 DSLR holder

2 week ago, there are a flora fest at Penang Botanical Garden and ton of people holding DSLR camera shooting over there, and my friend told me that seem like not flora fest, should be DSLR holder fest.

Yesterday I visit a shopping mall, and the mall having transformer models road show over there, a lot of people holder SLR Digital Cameras and keep on shooting the models. I hang around the shopping mall about half days, no matter where I went, I saw people holding DLSR camera.

In my opinion, people no longer going to buy compact digital camera, mostly will goes for SLR Digital Cameras because the price is almost same with normal compact digital camera and the advantage is more function and changeable lens.

If you planning to buy a DLSR cameras, probably you can consider nikon d90, is the enhancement model from my nikon D80. if you have extra budget, optional, probably you can get a flat panel tvs to view the photo you taken. It will bring you much more satisfaction for the photo you shoot.

• A network interface card (NIC), pronounced “nick,” is also called the LAN adapter, or just the network interface. This card typically goes into an ISA, PCI, or PCMCIA (PC card) slot in a computer and connects to the network medium. It then connects to other computers through the network media.
• Media refers to the various physical environments through which transmission signals pass. Common network media include twisted-pair, coaxial, and fiber-optic cable, and even the earth’s atmosphere through which wireless transmission occurs.
• A protocol is a set of rules. In the case of a network protocol, it is a set of rules by which computers communicate. The term “protocol suite” describes a set of several protocols that perform different functions related to different aspects of the communication process.
• Cisco IOS software which runs on Cisco equipment and devices, is the industry-leading and most widely deployed network system software. It delivers intelligent network services for enabling the rapid deployment of Internet applications.

Cisco IOS software provides a wide range of functionality, from basic connectivity, security, and network management to technically advanced services. The functionality of Cisco IOS software is the result of a technological evolution. First-generation networking devices could only store and forward data packets.

Today, Cisco IOS software can recognize, classify, and prioritize network traffic, optimize routing, support voice and video applications, and much more. Cisco IOS software runs on most Cisco routers and Cisco switches. These network devices carry most of the Internet traffic today.

• Network operating system (NOS) usually refers to server software such as Windows NT, Windows 2000 Server, Windows Server 2003, Novell NetWare, UNIX, and Linux. The term sometimes refers to the networking components of a client operating system such as Windows 95 or the Macintosh OS.
• Connectivity devices refer to several different device types, all of which are used to connect cable segments, connect two or more smaller networks (or subnets) into a larger network, or divide a large network into smaller ones. The term encompasses repeaters, hubs, switches, bridges, and routers.

The following are three categories of networks:

• A local-area network (LAN) is a network that is confined to a limited geographic area. This area can be a room, a floor, a building, or even an entire campus.
• A metropolitan-area network (MAN) is a network that is larger in size than a LAN and smaller in size than a WAN. This is a network that covers approximately the area of a large city or metropolitan area.
• A wide-area network (WAN) is made up of interconnected LANs. It spans wide geographic areas by using WAN links such as telephone lines or satellite technology to connect computers in different cities, countries, or even different continents.

Network structure is described in the following two ways:

• The logical topology is the path that the signals take from one computer to another. The logical topology may or may not correspond to the physical topology. For instance, a network can be a physical “star,” in which each computer connects to a central hub, but inside the hub the data can travel in a circle, making it a logical “ring.”

The physical topology refers to the layout or physical shape of the network, and includes the topologies in this table.

Bus - Computers arranged so that cabling goes from one to another in a linear fashion

Ring - When there are no clear beginning points or endpoints within a topology, forming a circle.

Star - If the systems “meet in the middle” by connecting to a central hub

Mesh - When multiple redundant connections make pathways to some or all of the endpoints.

All the while, we do have same dissatisfy with certain party, complaint on certain product and services, disagree with the decision that some authority made. but does out dissatisfy, complain, and disagree really bring the thing better?

Like my case, I do not satisfy with my apartment’s management, because they never do their job, but does complain really help?

Yesterday when I come back from the mainland, the road to town (so call jelutong “highway“) was fcuking JAM from the bridge. Stuck there about 45 minute only know what happen in front. Is because of our CEPAT, MESRA dan BETUL are “hardworking” doing blocking at there. We don’t what they blocking for, citizen are very dissatisfy with their “CEPAT, MESRA dan BETUL” and what can we do?

Same case during Chinese New Year, during the PEAK hour, they blocking the road in front of CHUNG LING HIGH SCHOOL, and make the traffic JAM along the Air Itam road and from FALIM. With their “hardworking“, bring suffer to the citizen. What can we do?

A lot cases that happening on me which I does not have the power make it better, just like I for to buy XMAS present to the legal thief and I get a summon from ‘CEPAT, MESRA dan BETUL“ when I parking at a legal parking area few year back.

If I am a blogger whom can bring influence to the society, I really want to represent all the citizen voice out our dissatisfaction on the blog. Not to said ANTI certain party, just would like to take back out RIGHT and hope to makes thing better.

Month ago when I blog about Cathay Cineplex Scam Promotion, I have bring up this issue to their head office at Singapore and end up I get back my right with Free Movie Ticket from Cathay Cinema. I guess because I blog about how bad their promotion was, so it bring back what I deserve to get.

If we does not know the correct way to voice out, it might bring a big trouble for us, end up might go in to the jail or prison if we does not know what should said and what should not said

Next week end have a Blogger Law Forum at Penang USM, this is a good oppurtunities for all the blogger who want to voice out the truth without fall into the mud. If you want to know your right as blogger, this Bloggers Law forum are free, organize at University Sains Malaysia (USM).

I will be there and find out what is a blogger right! Hope to make some different to the society.

So, any blogger with me, see you there. More information you can get it from Elawyer.com.my’s Blog

Registration: The admission to this Forum is FREE. However, due to limited seat, please R.S.V.P by sending your details (Name, Tel, Email, Occupation and Company/School) to forum@elawyer.com.my before 24 June 2009 or call 03-2782 5399 for more information.

Linux uses four basic file types:

• ordinary files
• directories
• symbolic links
• block and character device files

You determine a file’s type by issuing the ls -l command and reading the first character of each row of the output.
The typical output of the ls command is as follows:

$ ls –l
total 8
-rw-r–r–     1 root   root       22 Oct  6 15:33 anormalfile
brw-rw—-     2 root   disk  41,   0 May  5 1998 blockdev
crw-rw-rw-     2 root   root   5,   0 May  5 1998 characterdev
drwxr-xr-x     2 root   root     4096 Oct  6 15:33 subdir
lrwxrwxrwx     1 root   root       11 Oct  6 15:35 symbolic -> anormalfile

Ordinary files begin with a dash (-), directories begin with d, symbolic links begin with the character l, block devices are prefaced with the character b, and character devices begin with the letter c.

Ordinary files
An ordinary file can consist of any kind of data, including executable programs. Most of the files in the Linux file system are of this type.

Directories
A directory is a file that contains other files and directories, and provides pointers to them.
It performs a similar function to a folder in a filing cabinet, in that it enables you to group related files in an organized fashion. However, whereas folders can normally contain files only, directories can contain additional directories, often referred to as subdirectories.

Symbolic links
A symbolic – or soft – link points to the name and location of a completely separate file. So when you open, copy, move or otherwise refer to the link, the operation is in fact performed on the referenced file. This distinction is usually invisible to the user. If the referenced file is removed or renamed, the link is broken and an error occurs if you try to open it.

You can also create hard links. A hard link points to the actual data in a file in exactly the same way as an ordinary file does. Therefore, other than the name, there is no difference between the original file and a hard link that points to the same data, and both can be regarded as ordinary files. You can distinguish a hard link from any other ordinary file only by the number of links that each one has. The number of links is displayed in the second field of an ls -l listing. If this number is greater than one, then you know there are additional hard links to the data.

Device files
All the physical devices that Linux uses are represented by device files.
Device files can be classified as character special or block special. Character-special files represent devices that interact with Linux on a character-by-character, or serial, basis. Printers and terminals are examples of this type of device. Block-special files represent devices such as hard or floppy disks and CD-ROMs, which interact with Linux using blocks of data.

All the device files are contained in the /dev directory – for example, the file associated with the system’s first floppy drive is /dev/fd0.

Device files are extremely powerful because they enable users to access hardware devices such as disk drives, modems, and printers as though they were data files. Therefore, you can move, copy, and transfer data between such devices easily, often without having to use special commands or syntax.

Filenames and pathnames

Every file is assigned a filename, which can be up to 256 characters long. This name can consist of a mixture of uppercase and lowercase letters, numbers, and certain punctuation marks such as the period, dash, or underscore.

Certain characters cannot be used in filenames. For example, you cannot use characters that represent a field separator – such as a comma – or other special characters that have particular meaning to the shell. The special characters that you cannot use are

! @ # $ % ^ & * ( ) [ ] { } ‘ ” \ / | ; < > ‘

Pathnames
You can navigate between directories on the command line using pathnames. To use pathnames, you must understand the directory structure of the Linux file system. The highest-level directory in the Linux file system is the root directory, which is represented by a forward slash (/). Located under the root directory are the top-level directories, followed by one or more subdirectory levels.

File structure of a Linux file system
You can move between directories using relative or absolute pathnames.

A relative pathname starts with your current directory. For example, if you want to change to the expenses directory from within your home directory, you enter

cd expenses

Relative pathnames can begin with the name of a file or directory, or with symbolic references to the current directory (.) or its parent directory (..), but never with a forward slash.

A simple example of a Linux file system
An absolute pathname shows the full pathname from the root directory (/). For example, the following command allows you to move from your current directory directly to the applic subdirectory in the usr directory that’s located under the root directory:

cd /usr/applic

Inodes, blocks, and special files

Inodes
Every file is assigned a unique inode number. An inode is a structure that defines the file’s location and attributes. You can check for a file’s inode number using the -i option with the ls command. You can view the information that a file’s inode contains using the stat filename syntax. This command output (the stat results) displays the information related to the “results” file’s inode.

$ stat results
File: ”results”
Size: 8
Filetype: Regular file
Mode: (0644/-rw-r–r–)
Uid: (     0/     root)
Gid: (     0/     root)
Device: 3,7    Inode: 123256    Links: 1
Access: Tue Jul 25 16:45:00 2000 (00072.18:31:07)
Modify: Thu Jul 20 12:35:20 2000 (00077.22:40:47)
Change: Thu Jul 20 12:35:20 2000 (00077.22:40:47)

In this example, some of the attributes that are displayed include the file type, file size, the owner’s User ID (UID), the number of hard links associated with it, and the file’s creation, access, and modification times.

An inode does not store a file’s name. Filenames are stored in directories with their associated inode numbers. In the example of the stat command, the name of the file is obtained from the filename parameter that you entered.

Blocks
In the Linux file system, files are stored in blocks, which are identically sized segments of disk space. Generally, the size of a block varies from 512 bytes to 32 KB, depending on the Linux installation. The maximum size of a file depends on the block size used in the file system. For example, the maximum file size for an ext2 file system is 2 GB if it uses 512-byte blocks.

Disk systems retrieve data in block-sized chunks, so the larger the block size the more efficient the access. The problem with creating large blocks is that it can waste disk space. For example, if the block size is 4 KB and most files contain only a few bytes of data, most of the 4096 bytes of disk space is wasted for each file. But if you make the block sizes small, disk access will be relatively less efficient.

Some commands, such as df, output disk information in 1 KB blocks, even if the installation stores files in a different block size. A simple way to check your system’s block size is to use the du command to display the disk usage. In this example, the disk usage for all files beginning with “m” is displayed.

$ du -h m*
36k mail
4.0k mail.rc
12k mailcap
12k mailcap.vga
4.0k man.config
4.0k mc.global
148k midi
40k mime-magic
104k mime-magic.dat
8.0k mime.types
4.0k minicom.users
0 motd
4.0k mtab

In this example, the du command output displays the file sizes on the disk in increments of the block size, which is 4.0 KB in this case. One exception to this rule is when zero is displayed, which indicates that the file is completely empty.

Special files
In addition to other file types, Linux makes use of special files, which are system-defined files that perform unique functions when accessed.

Special files and their functions

For example, if you need to get rid of unwanted output from a command, you can redirect the output to the /dev/null file. In this example, any errors generated by the find command are redirected from stderr to /dev/null.

$ find / -n myfile 2> /dev/null

What hot this month CPU Magazine?

1. AMD Phenon II X4
2. Sapphire Vapor-X
3. Auzentech
4. 955 Black Edition
5. Radeon HD 4870
6. X-Fi Forte 7.1
7. Samsung SyncMaster 2233RZ
8. When three becomes four: We Mod the phenon II X3
9. Make yours eyes happy: we review seven LCD inside
10. Lock it down: we go deep with nine security siutes
11. Make your rig scream, low cost and no cost performance boosts
12. Straight from the valley of king: Egypt Mod
13. Q&A with david “dadi” perlmutter, the man behind mobility looks ahead.

Download CPU Magazine for July 2009 here:
hxxp://rapi*dshar*e.com/files/245032226/CPU_Magazine_07_2009.rar

What hot for this month PC World Magazine?

1. WIndows 7, Faster than Vista, I guess this should be real, because in my opinion, vista really suck.
2. 38 Tech Shortcuts to simplyfy your life. This will be benefit me, this is what expert need.
3. Some sub topic such as “Organize your office”, “protech your privacy”, “manage your media”,”take control of your online life”
4. Also “travel smarter”, “sync everything”,”save money”,”speed up and clearn up your PC”
5. Data Disaster, organized crime, wants your personal information, and they are getting it.
6. WIfi and Powerline, why your home network should have both.
7. Buying camera? Cameras under $200, best point and shoots for any shutter bug.

Download PC World Magazine for July 2009 here. hxxp://rapi*dsha*re.com/files/243583497/pcworld_072009.rar

What hot for this month Maximum PC Magazine

1. 38 Awesome application and utilities
2. 21 instant PC upgrades
3. Better, faster and stronger, release your PC;s untapped potential.
4. 6 budget videocards which pass, which fail.
5. 3 Trends that will save PC gaming.
6. 6 firefox tweaks to supercharge your browser.

Download Maximum PC Magazine for July 2009 herehxxp://rapi*dsh*are.com/files/243582312/MaxPC072009.rar