The Registry is a database used to store settings and options for the 32 bit versions of Microsoft Windows including Windows 95, 98, ME and NT/2000. It contains information and settings for all the hardware, software, users, and preferences of the PC. Whenever a user makes changes to a Control Panel settings, or File Associations, System Policies, or installed software, the changes are reflected and stored in the Registry.
The physical files that make up the registry are stored differently depending on your version of Windows; under Windows 95 & 98 it is contained in two hidden files in your Windows directory, called USER.DAT and SYSTEM.DAT, for Windows Me there is an additional CLASSES.DAT file, while under Windows NT/2000 the files are contained seperately in the %SystemRoot%\System32\Config directory. You can not edit these files directly, you must use a tool commonly known as a "Registry Editor" to make any changes (using registry editors will be discussed later in the article).
The Structure of The Registry
The Registry has a hierarchal structure, although it looks complicated the structure is similar to the directory structure on your hard disk, with Regedit being similar to Windows Explorer.
Each main branch (denoted by a folder icon in the Registry Editor, see left) is called a Hive, and Hives contains Keys. Each key can contain other keys (sometimes referred to as sub-keys), as well as Values. The values contain the actual information stored in the Registry. There are three types of values; String, Binary, and DWORD - the use of these depends upon the context.
There are six main branches, each containing a specific portion of the information stored in the Registry. They are as follows:
* HKEY_CLASSES_ROOT - This branch contains all of your file association mappings to support the drag-and-drop feature, OLE information, Windows shortcuts, and core aspects of the Windows user interface.
* HKEY_CURRENT_USER - This branch links to the section of HKEY_USERS appropriate for the user currently logged onto the PC and contains information such as logon names, desktop settings, and Start menu settings.
* HKEY_LOCAL_MACHINE - This branch contains computer specific information about the type of hardware, software, and other preferences on a given PC, this information is used for all users who log onto this computer.
* HKEY_USERS - This branch contains individual preferences for each user of the computer, each user is represented by a SID sub-key located under the main branch.
* HKEY_CURRENT_CONFIG - This branch links to the section of HKEY_LOCAL_MACHINE appropriate for the current hardware configuration.
* HKEY_DYN_DATA - This branch points to the part of HKEY_LOCAL_MACHINE, for use with the Plug-&-Play features of Windows, this section is dymanic and will change as devices are added and removed from the system.
Each registry value is stored as one of five main data types:
* REG_BINARY - This type stores the value as raw binary data. Most hardware component information is stored as binary data, and can be displayed in an editor in hexadecimal format.
* REG_DWORD - This type represents the data by a four byte number and is commonly used for boolean values, such as "0" is disabled and "1" is enabled. Additionally many parameters for device driver and services are this type, and can be displayed in REGEDT32 in binary, hexadecimal and decimal format, or in REGEDIT in hexadecimal and decimal format.
* REG_EXPAND_SZ - This type is an expandable data string that is string containing a variable to be replaced when called by an application. For example, for the following value, the string "%SystemRoot%" will replaced by the actual location of the directory containing the Windows NT system files. (This type is only available using an advanced registry editor such as REGEDT32)
* REG_MULTI_SZ - This type is a multiple string used to represent values that contain lists or multiple values, each entry is separated by a NULL character. (This type is only available using an advanced registry editor such as REGEDT32)
* REG_SZ - This type is a standard string, used to represent human readable text values.
Other data types not available through the standard registry editors include:
* REG_DWORD_LITTLE_ENDIAN - A 32-bit number in little-endian format.
* REG_DWORD_BIG_ENDIAN - A 32-bit number in big-endian format.
* REG_LINK - A Unicode symbolic link. Used internally; applications should not use this type.
* REG_NONE - No defined value type.
* REG_QWORD - A 64-bit number.
* REG_QWORD_LITTLE_ENDIAN - A 64-bit number in little-endian format.
* REG_RESOURCE_LIST - A device-driver resource list.
Editing The Registry
The Registry Editor (REGEDIT.EXE) is included with most version of Windows (although you won't find it on the Start Menu) it enables you to view, search and edit the data within the Registry. There are several methods for starting the Registry Editor, the simplest is to click on the Start button, then select Run, and in the Open box type "regedit", and if the Registry Editor is installed it should now open and look like the image below.
An alternative Registry Editor (REGEDT32.EXE) is available for use with Windows NT/2000, it includes some additional features not found in the standard version, including; the ability to view and modify security permissions, and being able to create and modify the extended string values REG_EXPAND_SZ & REG_MULTI_SZ.
Create a Shortcut to Regedit
This can be done by simply right-clicking on a blank area of your desktop, selecting New, then Shortcut, then in the Command line box enter "regedit.exe" and click Next, enter a friendly name (e.g. 'Registry Editor') then click Finish and now you can double click on the new icon to launch the Registry Editor.
Using Regedit to modify your Registry
Once you have started the Regedit you will notice that on the left side there is a tree with folders, and on the right the contents (values) of the currently selected folder.
Like Windows explorer, to expand a certain branch (see the structure of the registry section), click on the plus sign [+] to the left of any folder, or just double-click on the folder. To display the contents of a key (folder), just click the desired key, and look at the values listed on the right side. You can add a new key or value by selecting New from the Edit menu, or by right-clicking your mouse. And you can rename any value and almost any key with the same method used to rename files; right-click on an object and click rename, or click on it twice (slowly), or just press F2 on the keyboard. Lastly, you can delete a key or value by clicking on it, and pressing Delete on the keyboard, or by right-clicking on it, and choosing Delete.
Note: it is always a good idea to backup your registry before making any changes to it. It can be intimidating to a new user, and there is always the possibility of changing or deleting a critical setting causing you to have to reinstall the whole operating system. It's much better to be safe than sorry!
Importing and Exporting Registry Settings
A great feature of the Registry Editor is it's ability to import and export registry settings to a text file, this text file, identified by the .REG extension, can then be saved or shared with other people to easily modify local registry settings. You can see the layout of these text files by simply exporting a key to a file and opening it in Notepad, to do this using the Registry Editor select a key, then from the "Registry" menu choose "Export Registry File...", choose a filename and save. If you open this file in notepad you will see a file similar to the example below:
Quote:
REGEDIT4
[HKEY_LOCAL_MACHINE\SYSTEM\Setup]
"SetupType"=dword:00000000
"CmdLine"="setup -newsetup"
"SystemPrefix"=hex:c5,0b,00,00,00,40,36,02
The layout is quite simple, REGEDIT4 indicated the file type and version, [HKEY_LOCAL_MACHINE\SYSTEM\Setup] indicated the key the values are from, "SetupType"=dword:00000000 are the values themselves the portion after the "=" will vary depending on the type of value they are; DWORD, String or Binary.
So by simply editing this file to make the changes you want, it can then be easily distributed and all that need to be done is to double-click, or choose "Import" from the Registry menu, for the settings to be added to the system Registry.
Deleting keys or values using a REG file
It is also possible to delete keys and values using REG files. To delete a key start by using the same format as the the REG file above, but place a "-" symbol in front of the key name you want to delete. For example to delete the [HKEY_LOCAL_MACHINE\SYSTEM\Setup] key the reg file would look like this:
Quote:
REGEDIT4
[-HKEY_LOCAL_MACHINE\SYSTEM\Setup]
The format used to delete individual values is similar, but instead of a minus sign in front of the whole key, place it after the equal sign of the value. For example, to delete the value "SetupType" the file would look like:
Quote:
REGEDIT4
[HKEY_LOCAL_MACHINE\SYSTEM\Setup]
"SetupType"=-
Use this feature with care, as deleting the wrong key or value could cause major problems within the registry, so remember to always make a backup first.
Regedit Command Line Options
Regedit has a number of command line options to help automate it's use in either batch files or from the command prompt. Listed below are some of the options, please note the some of the functions are operating system specific.
* regedit.exe [options] [filename] [regpath]
* [filename] Import .reg file into the registry
* /s [filename] Silent import, i.e. hide confirmation box when importing files
* /e [filename] [regpath] Export the registry to [filename] starting at [regpath]
e.g. regedit /e file.reg HKEY_USERS\.DEFAULT
* /L:system Specify the location of the system.dat to use
* /R:user Specify the location of the user.dat to use
* /C [filename] Compress (Windows 98)
* /D [regpath] Delete the specified key (Windows 98)
Maintaining the Registry
How can you backup and restore the Registry?
Windows 95
Microsoft included a utility on the Windows 95 CD-ROM that lets you create backups of the Registry on your computer. The Microsoft Configuration Backup program, CFGBACK.EXE, can be found in the \Other\Misc\Cfgback directory on the Windows 95 CD-ROM. This utility lets you create up to nine different backup copies of the Registry, which it stores, with the extension RBK, in your \Windows directory. If your system is set up for multiple users, CFGBACK.EXE won't back up the USER.DAT file.
After you have backed up your Registry, you can copy the RBK file onto a floppy disk for safekeeping. However, to restore from a backup, the RBK file must reside in the \Windows directory. Windows 95 stores the backups in compressed form, which you can then restore only by using the CFGBACK.EXE utility.
Windows 98
Microsoft Windows 98 automatically creates a backup copy of the registry every time Windows starts, in addition to this you can manually create a backup using the Registry Checker utility by running SCANREGW.EXE from Start | Run menu.
What to do if you get a Corrupted Registry
Windows 95, 98 and NT all have a simple registry backup mechanism that is quite reliable, although you should never simply rely on it, remember to always make a backup first!
Windows 95
In the Windows directory there are several hidden files, four of these will be SYSTEM.DAT & USER.DAT, your current registry, and SYSTEM.DA0 & USER.DA0, a backup of your registry. Windows 9x has a nice reature in that every time it appears to start successfully it will copy the registry over these backup files, so just in case something goes wrong can can restore it to a known good state. To restore the registry follow these instruction:
[list=1]
* Click the Start button, and then click Shut Down.
* Click Restart The Computer In MS-DOS Mode, then click Yes.
* Change to your Windows directory. For example, if your Windows directory is c:\windows, you would type the following:
cd c:\windows
* Type the following commands, pressing ENTER after each one. (Note that SYSTEM.DA0 and USER.DA0 contain the number zero.)
attrib -h -r -s system.dat
attrib -h -r -s system.da0
copy system.da0 system.dat
attrib -h -r -s user.dat
attrib -h -r -s user.da0
copy user.da0 user.dat
* Restart your computer.
Following this procedure will restore your registry to its state when you last successfully started your computer.
If all else fails, there is a file on your hard disk named SYSTEM.1ST that was created when Windows 95 was first successfully installed. If necessary you could also change the file attributes of this file from read-only and hidden to archive to copy the file to C:\WINDOWS\SYSTEM.DAT.
Windows NT
On Windows NT you can use either the "Last Known Good" option or RDISK to restore to registry to a stable working configuration.
How can I clean out old data from the Registry?
Although it's possible to manually go through the Registry and delete unwanted entries, Microsoft provides a tool to automate the process, the program is called RegClean. RegClean analyzes Windows Registry keys stored in a common location in the Windows Registry. It finds keys that contain erroneous values, it removes them from the Windows Registry after having recording those entries in the Undo.Reg file.
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Friday, May 30, 2008
Thursday, May 29, 2008
How Linux boots
As it turns out, there isn't much to the boot process:
1. A boot loader finds the kernel image on the disk, loads it into memory, and starts it.
2. The kernel initializes the devices and its drivers.
3. The kernel mounts the root filesystem.
4. The kernel starts a program called init.
5. init sets the rest of the processes in motion.
6. The last processes that init starts as part of the boot sequence allow you to log in.
Identifying each stage of the boot process is invaluable in fixing boot problems and understanding the system as a whole. To start, zero in on the boot loader, which is the initial screen or prompt you get after the computer does its power-on self-test, asking which operating system to run. After you make a choice, the boot loader runs the Linux kernel, handing control of the system to the kernel.
There is a detailed discussion of the kernel elsewhere in this book from which this article is excerpted. This article covers the kernel initialization stage, the stage when the kernel prints a bunch of messages about the hardware present on the system. The kernel starts init just after it displays a message proclaiming that the kernel has mounted the root filesystem:
VFS: Mounted root (ext2 filesystem) readonly.
Soon after, you will see a message about init starting, followed by system service startup messages, and finally you get a login prompt of some sort.
NOTE On Red Hat Linux, the init note is especially obvious, because it "welcomes" you to "Red Hat Linux." All messages thereafter show success or failure in brackets at the right-hand side of the screen.
Most of this chapter deals with init, because it is the part of the boot sequence where you have the most control.
init
There is nothing special about init. It is a program just like any other on the Linux system, and you'll find it in /sbin along with other system binaries. The main purpose of init is to start and stop other programs in a particular sequence. All you have to know is how this sequence works.
There are a few different variations, but most Linux distributions use the System V style discussed here. Some distributions use a simpler version that resembles the BSD init, but you are unlikely to encounter this.
Runlevels
At any given time on a Linux system, a certain base set of processes is running. This state of the machine is called its runlevel, and it is denoted with a number from 0 through 6. The system spends most of its time in a single runlevel. However, when you shut the machine down, init switches to a different runlevel in order to terminate the system services in an orderly fashion and to tell the kernel to stop. Yet another runlevel is for single-user mode, discussed later.
The easiest way to get a handle on runlevels is to examine the init configuration file, /etc/inittab. Look for a line like the following:
id:5:initdefault:
This line means that the default runlevel on the system is 5. All lines in the inittab file take this form, with four fields separated by colons occurring in the following order:
# A unique identifier (a short string, such as id in the preceding example)
# The applicable runlevel number(s)
# The action that init should take (in the preceding example, the action is to set the default runlevel to 5)
# A command to execute (optional)
There is no command to execute in the preceding initdefault example because a command doesn't make sense in the context of setting the default runlevel. Look a little further down in inittab, until you see a line like this:
l5:5:wait:/etc/rc.d/rc 5
This line triggers most of the system configuration and services through the rc*.d and init.d directories. You can see that init is set to execute a command called /etc/rc.d/rc 5 when in runlevel 5. The wait action tells when and how init runs the command: run rc 5 once when entering runlevel 5, and then wait for this command to finish before doing anything else.
There are several different actions in addition to initdefault and wait, especially pertaining to power management, and the inittab(5) manual page tells you all about them. The ones that you're most likely to encounter are explained in the following sections.
respawn
The respawn action causes init to run the command that follows, and if the command finishes executing, to run it again. You're likely to see something similar to this line in your inittab file:
1:2345:respawn:/sbin/mingetty tty1
The getty programs provide login prompts. The preceding line is for the first virtual console (/dev/tty1), the one you see when you press ALT-F1 or CONTROL-ALT-F1. The respawn action brings the login prompt back after you log out.
ctrlaltdel
The ctrlaltdel action controls what the system does when you press CONTROL-ALT-DELETE on a virtual console. On most systems, this is some sort of reboot command using the shutdown command.
sysinit
The sysinit action is the very first thing that init should run when it starts up, before entering any runlevels.
How processes in runlevels start
You are now ready to learn how init starts the system services, just before it lets you log in. Recall this inittab line from earlier:
l5:5:wait:/etc/rc.d/rc 5
This small line triggers many other programs. rc stands for run commands, and you will hear people refer to the commands as scripts, programs, or services. So, where are these commands, anyway?
For runlevel 5, in this example, the commands are probably either in /etc/rc.d/rc5.d or /etc/rc5.d. Runlevel 1 uses rc1.d, runlevel 2 uses rc2.d, and so on. You might find the following items in the rc5.d directory:
S10sysklogd S20ppp S99gpm
S12kerneld S25netstd_nfs S99httpd
S15netstd_init S30netstd_misc S99rmnologin
S18netbase S45pcmcia S99sshd
S20acct S89atd
S20logoutd S89cron
The rc 5 command starts programs in this runlevel directory by running the following commands:
S10sysklogd start
S12kerneld start
S15netstd_init start
S18netbase start
...
S99sshd start
Notice the start argument in each command. The S in a command name means that the command should run in start mode, and the number (00 through 99) determines where in the sequence rc starts the command.
The rc*.d commands are usually shell scripts that start programs in /sbin or /usr/sbin. Normally, you can figure out what one of the commands actually does by looking at the script with less or another pager program.
You can start one of these services by hand. For example, if you want to start the httpd Web server program manually, run S99httpd start. Similarly, if you ever need to kill one of the services when the machine is on, you can run the command in the rc*.d directory with the stop argument (S99httpd stop, for instance).
Some rc*.d directories contain commands that start with K (for "kill," or stop mode). In this case, rc runs the command with the stop argument instead of start. You are most likely to encounter K commands in runlevels that shut the system down.
Adding and removing services
If you want to add, delete, or modify services in the rc*.d directories, you need to take a closer look at the files inside. A long listing reveals a structure like this:
lrwxrwxrwx . . . S10sysklogd -> ../init.d/sysklogd
lrwxrwxrwx . . . S12kerneld -> ../init.d/kerneld
lrwxrwxrwx . . . S15netstd_init -> ../init.d/netstd_init
lrwxrwxrwx . . . S18netbase -> ../init.d/netbase
...
The commands in an rc*.d directory are actually symbolic links to files in an init.d directory, usually in /etc or /etc/rc.d. Linux distributions contain these links so that they can use the same startup scripts for all runlevels. This convention is by no means a requirement, but it often makes organization a little easier.
To prevent one of the commands in the init.d directory from running in a particular runlevel, you might think of removing the symbolic link in the appropriate rc*.d directory. This does work, but if you make a mistake and ever need to put the link back in place, you might have trouble remembering the exact name of the link. Therefore, you shouldn't remove links in the rc*.d directories, but rather, add an underscore (_) to the beginning of the link name like this:
mv S99httpd _S99httpd
At boot time, rc ignores _S99httpd because it doesn't start with S or K. Furthermore, the original name is still obvious, and you have quick access to the command if you're in a pinch and need to start it by hand.
To add a service, you must create a script like the others in the init.d directory and then make a symbolic link in the correct rc*.d directory. The easiest way to write a script is to examine the scripts already in init.d, make a copy of one that you understand, and modify the copy.
When adding a service, make sure that you choose an appropriate place in the boot sequence to start the service. If the service starts too soon, it may not work, due to a dependency on some other service. For non-essential services, most systems administrators prefer numbers in the 90s, after most of the services that came with the system.
Linux distributions usually come with a command to enable and disable services in the rc*.d directories. For example, in Debian, the command is update-rc.d, and in Red Hat Linux, the command is chkconfig. Graphical user interfaces are also available. Using these programs helps keep the startup directories consistent and helps with upgrades.
HINT: One of the most common Linux installation problems is an improperly configured XFree86 server that flicks on and off, making the system unusable on console. To stop this behavior, boot into single-user mode and alter your runlevel or runlevel services. Look for something containing xdm, gdm, or kdm in your rc*.d directories, or your /etc/inittab.
Controlling init
Occasionally, you need to give init a little kick to tell it to switch runlevels, to re-read the inittab file, or just to shut down the system. Because init is always the first process on a system, its process ID is always 1.
You can control init with telinit. For example, if you want to switch to runlevel 3, use this command:
telinit 3
When switching runlevels, init tries to kill off any processes that aren't in the inittab file for the new runlevel. Therefore, you should be careful about changing runlevels.
When you need to add or remove respawning jobs or make any other change to the inittab file, you must tell init about the change and cause it to re-read the file. Some people use kill -HUP 1 to tell init to do this. This traditional method works on most versions of Unix, as long as you type it correctly. However, you can also run this telinit command:
telinit q
You can also use telinit s to switch to single-user mode.
Shutting down
init also controls how the system shuts down and reboots. The proper way to shut down a Linux machine is to use the shutdown command.
There are two basic ways to use shutdown. If you halt the system, it shuts the machine down and keeps it down. To make the machine halt immediately, use this command:
shutdown -h now
On most modern machines with reasonably recent versions of Linux, a halt cuts the power to the machine. You can also reboot the machine. For a reboot, use -r instead of -h.
The shutdown process takes several seconds. You should never reset or power off a machine during this stage.
In the preceding example, now is the time to shut down. This argument is mandatory, but there are many ways of specifying it. If you want the machine to go down sometime in the future, one way is to use +n, where n is the number of minutes shutdown should wait before doing its work. For other options, look at the shutdown(8) manual page.
To make the system reboot in 10 minutes, run this command:
shutdown -r +10
On Linux, shutdown notifies anyone logged on that the machine is going down, but it does little real work. If you specify a time other than now, shutdown creates a file called /etc/nologin. When this file is present, the system prohibits logins by anyone except the superuser.
When system shutdown time finally arrives, shutdown tells init to switch to runlevel 0 for a halt and runlevel 6 for a reboot. When init enters runlevel 0 or 6, all of the following takes place, which you can verify by looking at the scripts inside rc0.d and rc6.d:
1. init kills every process that it can (as it would when switching to any other runlevel).
# The initial rc0.d/rc6.d commands run, locking system files into place and making other preparations for shutdown.
# The next rc0.d/rc6.d commands unmount all filesystems other than the root.
# Further rc0.d/rc6.d commands remount the root filesystem read-only.
# Still more rc0.d/rc6.d commands write all buffered data out to the filesystem with the sync program.
# The final rc0.d/rc6.d commands tell the kernel to reboot or stop with the reboot, halt, or poweroff program.
The reboot and halt programs behave differently for each runlevel, potentially causing confusion. By default, these programs call shutdown with the -r or -h options, but if the system is already at the halt or reboot runlevel, the programs tell the kernel to shut itself off immediately. If you really want to shut your machine down in a hurry (disregarding any possible damage from a disorderly shutdown), use the -f option.
1. A boot loader finds the kernel image on the disk, loads it into memory, and starts it.
2. The kernel initializes the devices and its drivers.
3. The kernel mounts the root filesystem.
4. The kernel starts a program called init.
5. init sets the rest of the processes in motion.
6. The last processes that init starts as part of the boot sequence allow you to log in.
Identifying each stage of the boot process is invaluable in fixing boot problems and understanding the system as a whole. To start, zero in on the boot loader, which is the initial screen or prompt you get after the computer does its power-on self-test, asking which operating system to run. After you make a choice, the boot loader runs the Linux kernel, handing control of the system to the kernel.
There is a detailed discussion of the kernel elsewhere in this book from which this article is excerpted. This article covers the kernel initialization stage, the stage when the kernel prints a bunch of messages about the hardware present on the system. The kernel starts init just after it displays a message proclaiming that the kernel has mounted the root filesystem:
VFS: Mounted root (ext2 filesystem) readonly.
Soon after, you will see a message about init starting, followed by system service startup messages, and finally you get a login prompt of some sort.
NOTE On Red Hat Linux, the init note is especially obvious, because it "welcomes" you to "Red Hat Linux." All messages thereafter show success or failure in brackets at the right-hand side of the screen.
Most of this chapter deals with init, because it is the part of the boot sequence where you have the most control.
init
There is nothing special about init. It is a program just like any other on the Linux system, and you'll find it in /sbin along with other system binaries. The main purpose of init is to start and stop other programs in a particular sequence. All you have to know is how this sequence works.
There are a few different variations, but most Linux distributions use the System V style discussed here. Some distributions use a simpler version that resembles the BSD init, but you are unlikely to encounter this.
Runlevels
At any given time on a Linux system, a certain base set of processes is running. This state of the machine is called its runlevel, and it is denoted with a number from 0 through 6. The system spends most of its time in a single runlevel. However, when you shut the machine down, init switches to a different runlevel in order to terminate the system services in an orderly fashion and to tell the kernel to stop. Yet another runlevel is for single-user mode, discussed later.
The easiest way to get a handle on runlevels is to examine the init configuration file, /etc/inittab. Look for a line like the following:
id:5:initdefault:
This line means that the default runlevel on the system is 5. All lines in the inittab file take this form, with four fields separated by colons occurring in the following order:
# A unique identifier (a short string, such as id in the preceding example)
# The applicable runlevel number(s)
# The action that init should take (in the preceding example, the action is to set the default runlevel to 5)
# A command to execute (optional)
There is no command to execute in the preceding initdefault example because a command doesn't make sense in the context of setting the default runlevel. Look a little further down in inittab, until you see a line like this:
l5:5:wait:/etc/rc.d/rc 5
This line triggers most of the system configuration and services through the rc*.d and init.d directories. You can see that init is set to execute a command called /etc/rc.d/rc 5 when in runlevel 5. The wait action tells when and how init runs the command: run rc 5 once when entering runlevel 5, and then wait for this command to finish before doing anything else.
There are several different actions in addition to initdefault and wait, especially pertaining to power management, and the inittab(5) manual page tells you all about them. The ones that you're most likely to encounter are explained in the following sections.
respawn
The respawn action causes init to run the command that follows, and if the command finishes executing, to run it again. You're likely to see something similar to this line in your inittab file:
1:2345:respawn:/sbin/mingetty tty1
The getty programs provide login prompts. The preceding line is for the first virtual console (/dev/tty1), the one you see when you press ALT-F1 or CONTROL-ALT-F1. The respawn action brings the login prompt back after you log out.
ctrlaltdel
The ctrlaltdel action controls what the system does when you press CONTROL-ALT-DELETE on a virtual console. On most systems, this is some sort of reboot command using the shutdown command.
sysinit
The sysinit action is the very first thing that init should run when it starts up, before entering any runlevels.
How processes in runlevels start
You are now ready to learn how init starts the system services, just before it lets you log in. Recall this inittab line from earlier:
l5:5:wait:/etc/rc.d/rc 5
This small line triggers many other programs. rc stands for run commands, and you will hear people refer to the commands as scripts, programs, or services. So, where are these commands, anyway?
For runlevel 5, in this example, the commands are probably either in /etc/rc.d/rc5.d or /etc/rc5.d. Runlevel 1 uses rc1.d, runlevel 2 uses rc2.d, and so on. You might find the following items in the rc5.d directory:
S10sysklogd S20ppp S99gpm
S12kerneld S25netstd_nfs S99httpd
S15netstd_init S30netstd_misc S99rmnologin
S18netbase S45pcmcia S99sshd
S20acct S89atd
S20logoutd S89cron
The rc 5 command starts programs in this runlevel directory by running the following commands:
S10sysklogd start
S12kerneld start
S15netstd_init start
S18netbase start
...
S99sshd start
Notice the start argument in each command. The S in a command name means that the command should run in start mode, and the number (00 through 99) determines where in the sequence rc starts the command.
The rc*.d commands are usually shell scripts that start programs in /sbin or /usr/sbin. Normally, you can figure out what one of the commands actually does by looking at the script with less or another pager program.
You can start one of these services by hand. For example, if you want to start the httpd Web server program manually, run S99httpd start. Similarly, if you ever need to kill one of the services when the machine is on, you can run the command in the rc*.d directory with the stop argument (S99httpd stop, for instance).
Some rc*.d directories contain commands that start with K (for "kill," or stop mode). In this case, rc runs the command with the stop argument instead of start. You are most likely to encounter K commands in runlevels that shut the system down.
Adding and removing services
If you want to add, delete, or modify services in the rc*.d directories, you need to take a closer look at the files inside. A long listing reveals a structure like this:
lrwxrwxrwx . . . S10sysklogd -> ../init.d/sysklogd
lrwxrwxrwx . . . S12kerneld -> ../init.d/kerneld
lrwxrwxrwx . . . S15netstd_init -> ../init.d/netstd_init
lrwxrwxrwx . . . S18netbase -> ../init.d/netbase
...
The commands in an rc*.d directory are actually symbolic links to files in an init.d directory, usually in /etc or /etc/rc.d. Linux distributions contain these links so that they can use the same startup scripts for all runlevels. This convention is by no means a requirement, but it often makes organization a little easier.
To prevent one of the commands in the init.d directory from running in a particular runlevel, you might think of removing the symbolic link in the appropriate rc*.d directory. This does work, but if you make a mistake and ever need to put the link back in place, you might have trouble remembering the exact name of the link. Therefore, you shouldn't remove links in the rc*.d directories, but rather, add an underscore (_) to the beginning of the link name like this:
mv S99httpd _S99httpd
At boot time, rc ignores _S99httpd because it doesn't start with S or K. Furthermore, the original name is still obvious, and you have quick access to the command if you're in a pinch and need to start it by hand.
To add a service, you must create a script like the others in the init.d directory and then make a symbolic link in the correct rc*.d directory. The easiest way to write a script is to examine the scripts already in init.d, make a copy of one that you understand, and modify the copy.
When adding a service, make sure that you choose an appropriate place in the boot sequence to start the service. If the service starts too soon, it may not work, due to a dependency on some other service. For non-essential services, most systems administrators prefer numbers in the 90s, after most of the services that came with the system.
Linux distributions usually come with a command to enable and disable services in the rc*.d directories. For example, in Debian, the command is update-rc.d, and in Red Hat Linux, the command is chkconfig. Graphical user interfaces are also available. Using these programs helps keep the startup directories consistent and helps with upgrades.
HINT: One of the most common Linux installation problems is an improperly configured XFree86 server that flicks on and off, making the system unusable on console. To stop this behavior, boot into single-user mode and alter your runlevel or runlevel services. Look for something containing xdm, gdm, or kdm in your rc*.d directories, or your /etc/inittab.
Controlling init
Occasionally, you need to give init a little kick to tell it to switch runlevels, to re-read the inittab file, or just to shut down the system. Because init is always the first process on a system, its process ID is always 1.
You can control init with telinit. For example, if you want to switch to runlevel 3, use this command:
telinit 3
When switching runlevels, init tries to kill off any processes that aren't in the inittab file for the new runlevel. Therefore, you should be careful about changing runlevels.
When you need to add or remove respawning jobs or make any other change to the inittab file, you must tell init about the change and cause it to re-read the file. Some people use kill -HUP 1 to tell init to do this. This traditional method works on most versions of Unix, as long as you type it correctly. However, you can also run this telinit command:
telinit q
You can also use telinit s to switch to single-user mode.
Shutting down
init also controls how the system shuts down and reboots. The proper way to shut down a Linux machine is to use the shutdown command.
There are two basic ways to use shutdown. If you halt the system, it shuts the machine down and keeps it down. To make the machine halt immediately, use this command:
shutdown -h now
On most modern machines with reasonably recent versions of Linux, a halt cuts the power to the machine. You can also reboot the machine. For a reboot, use -r instead of -h.
The shutdown process takes several seconds. You should never reset or power off a machine during this stage.
In the preceding example, now is the time to shut down. This argument is mandatory, but there are many ways of specifying it. If you want the machine to go down sometime in the future, one way is to use +n, where n is the number of minutes shutdown should wait before doing its work. For other options, look at the shutdown(8) manual page.
To make the system reboot in 10 minutes, run this command:
shutdown -r +10
On Linux, shutdown notifies anyone logged on that the machine is going down, but it does little real work. If you specify a time other than now, shutdown creates a file called /etc/nologin. When this file is present, the system prohibits logins by anyone except the superuser.
When system shutdown time finally arrives, shutdown tells init to switch to runlevel 0 for a halt and runlevel 6 for a reboot. When init enters runlevel 0 or 6, all of the following takes place, which you can verify by looking at the scripts inside rc0.d and rc6.d:
1. init kills every process that it can (as it would when switching to any other runlevel).
# The initial rc0.d/rc6.d commands run, locking system files into place and making other preparations for shutdown.
# The next rc0.d/rc6.d commands unmount all filesystems other than the root.
# Further rc0.d/rc6.d commands remount the root filesystem read-only.
# Still more rc0.d/rc6.d commands write all buffered data out to the filesystem with the sync program.
# The final rc0.d/rc6.d commands tell the kernel to reboot or stop with the reboot, halt, or poweroff program.
The reboot and halt programs behave differently for each runlevel, potentially causing confusion. By default, these programs call shutdown with the -r or -h options, but if the system is already at the halt or reboot runlevel, the programs tell the kernel to shut itself off immediately. If you really want to shut your machine down in a hurry (disregarding any possible damage from a disorderly shutdown), use the -f option.
How To Access Your Folders From Your Taskbar
This is an easy way to get to the folders on your system without having to open a Windows Explorer Window every time you want to access files. I find it very useful to have this feature as it allows me to access my Folders and Drives immediately and saves me a lot of time.
This works in Windows XP:
1. Right Click an empty spot on your Taskbar (Between your Start Button and your System Tray).
2. Click Toolbars.
3. Click New Toolbar.
4. A Small Window will Open that allows you to pick the folder you wish to make a Toolbar. If you want to access your Desktop Without having to minimize all your windows. Just Pick Desktop. If you want to access ONLY your My Documents Folder, Select that. Any folder will work for this.
5. Click OK.
The New Tool bar will appear at the bottom of your screen next to your System Tray.
If you find this to be not useful, Repeat Steps 1 and 2 and then check click the Toolbar you created that has a check mark next to it. And it will disappear.
This works in Windows XP:
1. Right Click an empty spot on your Taskbar (Between your Start Button and your System Tray).
2. Click Toolbars.
3. Click New Toolbar.
4. A Small Window will Open that allows you to pick the folder you wish to make a Toolbar. If you want to access your Desktop Without having to minimize all your windows. Just Pick Desktop. If you want to access ONLY your My Documents Folder, Select that. Any folder will work for this.
5. Click OK.
The New Tool bar will appear at the bottom of your screen next to your System Tray.
If you find this to be not useful, Repeat Steps 1 and 2 and then check click the Toolbar you created that has a check mark next to it. And it will disappear.
Beep codes Error codes
After repeated requests for beep codes i have decided to post them here maybe they could be pinned
Standard Original IBM POST Error Codes
Code Description
1 short beep System is OK
2 short beeps POST Error - error code shown on screen No beep Power supply or system board problem Continuous beep Power supply, system board, or keyboard problem Repeating short beeps Power supply or system board problem
1 long, 1 short beep System board problem
1 long, 2 short beeps Display adapter problem (MDA, CGA)
1 long, 3 short beeps Display adapter problem (EGA)
3 long beeps 3270 keyboard card
IBM POST Diagnostic Code Descriptions
Code Description
100 - 199 System Board
200 - 299 Memory
300 - 399 Keyboard
400 - 499 Monochrome Display
500 - 599 Colour/Graphics Display
600 - 699 Floppy-disk drive and/or Adapter
700 - 799 Math Coprocessor
900 - 999 Parallel Printer Port
1000 - 1099 Alternate Printer Adapter
1100 - 1299 Asynchronous Communication Device, Adapter, or Port
1300 - 1399 Game Port
1400 - 1499 Colour/Graphics Printer
1500 - 1599 Synchronous Communication Device, Adapter, or Port
1700 - 1799 Hard Drive and/or Adapter
1800 - 1899 Expansion Unit (XT)
2000 - 2199 Bisynchronous Communication Adapter
2400 - 2599 EGA system-board Video (MCA)
3000 - 3199 LAN Adapter
4800 - 4999 Internal Modem
7000 - 7099 Phoenix BIOS Chips
7300 - 7399 3.5" Disk Drive
8900 - 8999 MIDI Adapter
11200 - 11299 SCSI Adapter
21000 - 21099 SCSI Fixed Disk and Controller
21500 - 21599 SCSI CD-ROM System
AMI BIOS Beep Codes
Code Description
1 Short Beep System OK
2 Short Beeps Parity error in the first 64 KB of memory
3 Short Beeps Memory failure in the first 64 KB
4 Short Beeps Memory failure in the first 64 KB Operational of memory
or Timer 1 on the motherboard is not functioning
5 Short Beeps The CPU on the motherboard generated an error
6 Short Beeps The keyboard controller may be bad. The BIOS cannot switch to protected mode
7 Short Beeps The CPU generated an exception interrupt
8 Short Beeps The system video adapter is either missing, or its memory is faulty
9 Short Beeps The ROM checksum value does not match the value encoded in the BIOS
10 Short Beeps The shutdown register for CMOS RAM failed
11 Short Beeps The external cache is faulty
1 Long, 3 Short Beeps Memory Problems
1 Long, 8 Short Beeps Video Card Problems
Phoenix BIOS Beep Codes
Note - Phoenix BIOS emits three sets of beeps, separated by a brief pause.
Code Description
1-1-3 CMOS read/write failure
1-1-4 ROM BIOS checksum error
1-2-1 Programmable interval timer failure
1-2-2 DMA initialisation failure
1-2-3 DMA page register read/write failure
1-3-1 RAM refresh verification failure
1-3-3 First 64k RAM chip or data line failure
1-3-4 First 64k RAM odd/even logic failure
1-4-1 Address line failure first 64k RAM
1-4-2 Parity failure first 64k RAM
2-_-_ Faulty Memory
3-1-_ Faulty Motherboard
3-2-4 Keyboard controller Test failure
3-3-4 Screen initialisation failure
3-4-1 Screen retrace test failure
3-4-2 Search for video ROM in progress
4-2-1 Timer tick interrupt in progress or failure
4-2-2 Shutdown test in progress or failure
4-2-3 Gate A20 failure
4-2-4 Unexpected interrupt in protected mode
4-3-1 RAM test in progress or failure>ffffh
4-3-2 Faulty Motherboard
4-3-3 Interval timer channel 2 test or failure
4-3-4 Time of Day clock test failure
4-4-1 Serial port test or failure
4-4-2 Parallel port test or failure
4-4-3 Math coprocessor test or failure
Low 1-1-2 System Board select failure
Low 1-1-3 Extended CMOS RAM failure
Standard Original IBM POST Error Codes
Code Description
1 short beep System is OK
2 short beeps POST Error - error code shown on screen No beep Power supply or system board problem Continuous beep Power supply, system board, or keyboard problem Repeating short beeps Power supply or system board problem
1 long, 1 short beep System board problem
1 long, 2 short beeps Display adapter problem (MDA, CGA)
1 long, 3 short beeps Display adapter problem (EGA)
3 long beeps 3270 keyboard card
IBM POST Diagnostic Code Descriptions
Code Description
100 - 199 System Board
200 - 299 Memory
300 - 399 Keyboard
400 - 499 Monochrome Display
500 - 599 Colour/Graphics Display
600 - 699 Floppy-disk drive and/or Adapter
700 - 799 Math Coprocessor
900 - 999 Parallel Printer Port
1000 - 1099 Alternate Printer Adapter
1100 - 1299 Asynchronous Communication Device, Adapter, or Port
1300 - 1399 Game Port
1400 - 1499 Colour/Graphics Printer
1500 - 1599 Synchronous Communication Device, Adapter, or Port
1700 - 1799 Hard Drive and/or Adapter
1800 - 1899 Expansion Unit (XT)
2000 - 2199 Bisynchronous Communication Adapter
2400 - 2599 EGA system-board Video (MCA)
3000 - 3199 LAN Adapter
4800 - 4999 Internal Modem
7000 - 7099 Phoenix BIOS Chips
7300 - 7399 3.5" Disk Drive
8900 - 8999 MIDI Adapter
11200 - 11299 SCSI Adapter
21000 - 21099 SCSI Fixed Disk and Controller
21500 - 21599 SCSI CD-ROM System
AMI BIOS Beep Codes
Code Description
1 Short Beep System OK
2 Short Beeps Parity error in the first 64 KB of memory
3 Short Beeps Memory failure in the first 64 KB
4 Short Beeps Memory failure in the first 64 KB Operational of memory
or Timer 1 on the motherboard is not functioning
5 Short Beeps The CPU on the motherboard generated an error
6 Short Beeps The keyboard controller may be bad. The BIOS cannot switch to protected mode
7 Short Beeps The CPU generated an exception interrupt
8 Short Beeps The system video adapter is either missing, or its memory is faulty
9 Short Beeps The ROM checksum value does not match the value encoded in the BIOS
10 Short Beeps The shutdown register for CMOS RAM failed
11 Short Beeps The external cache is faulty
1 Long, 3 Short Beeps Memory Problems
1 Long, 8 Short Beeps Video Card Problems
Phoenix BIOS Beep Codes
Note - Phoenix BIOS emits three sets of beeps, separated by a brief pause.
Code Description
1-1-3 CMOS read/write failure
1-1-4 ROM BIOS checksum error
1-2-1 Programmable interval timer failure
1-2-2 DMA initialisation failure
1-2-3 DMA page register read/write failure
1-3-1 RAM refresh verification failure
1-3-3 First 64k RAM chip or data line failure
1-3-4 First 64k RAM odd/even logic failure
1-4-1 Address line failure first 64k RAM
1-4-2 Parity failure first 64k RAM
2-_-_ Faulty Memory
3-1-_ Faulty Motherboard
3-2-4 Keyboard controller Test failure
3-3-4 Screen initialisation failure
3-4-1 Screen retrace test failure
3-4-2 Search for video ROM in progress
4-2-1 Timer tick interrupt in progress or failure
4-2-2 Shutdown test in progress or failure
4-2-3 Gate A20 failure
4-2-4 Unexpected interrupt in protected mode
4-3-1 RAM test in progress or failure>ffffh
4-3-2 Faulty Motherboard
4-3-3 Interval timer channel 2 test or failure
4-3-4 Time of Day clock test failure
4-4-1 Serial port test or failure
4-4-2 Parallel port test or failure
4-4-3 Math coprocessor test or failure
Low 1-1-2 System Board select failure
Low 1-1-3 Extended CMOS RAM failure
Computer Acronyms
ADSL - Asymmetric Digital Subscriber Line
AGP - Accelerated Graphics Port
ALI - Acer Labs, Incorporated
ALU - Arithmetic Logic Unit
AMD - Advanced Micro Devices
APC - American Power Conversion
ASCII - American Standard Code for Information Interchange
ASIC - Application Specific Integrated Circuit
ASPI - Advanced SCSI Programming Interface
AT - Advanced Technology
ATI - ATI Technologies Inc.
ATX - Advanced Technology Extended
--- B ---BFG - BFG Technologies
BIOS - Basic Input Output System
BNC - Barrel Nut Connector
--- C ---
CAS - Column Address Signal
CD - Compact Disk
CDR - Compact Disk Recorder
CDRW - Compact Disk Re-Writer
CD-ROM - Compact Disk - Read Only Memory
CFM - Cubic Feet per Minute (ft�/min)
CMOS - Complementary Metal Oxide Semiconductor
CPU - Central Processing Unit
CTX - CTX Technology Corporation (Commited to Excellence)
--- D ---
DDR - Double Data Rate
DDR-SDRAM - Double Data Rate - Synchronous Dynamic Random Access Memory
DFI - DFI Inc. (Design for Innovation)
DIMM - Dual Inline Memory Module
DRAM - Dynamic Random Access Memory
DPI - Dots Per Inch
DSL - See ASDL
DVD - Digital Versatile Disc
DVD-RAM - Digital Versatile Disk - Random Access Memory
--- E ---
ECC - Error Correction Code
ECS - Elitegroup Computer Systems
EDO - Extended Data Out
EEPROM - Electrically Erasable Programmable Read-Only Memory
EPROM - Erasable Programmable Read-Only Memory
EVGA - EVGA Corporation
--- F ---
FC-PGA - Flip Chip Pin Grid Array
FDC - Floppy Disk Controller
FDD - Floppy Disk Drive
FPS - Frame Per Second
FPU - Floating Point Unit
FSAA - Full Screen Anti-Aliasing
FS - For Sale
FSB - Front Side Bus
--- G ---
GB - Gigabytes
GBps - Gigabytes per second or Gigabits per second
GDI - Graphical Device Interface
GHz - GigaHertz
--- H ---
HDD - Hard Disk Drive
HIS - Hightech Information System Limited
HP - Hewlett-Packard Development Company
HSF - Heatsink-Fan
--- I ---
IBM - International Business Machines Corporation
IC - Integrated Circuit
IDE - Integrated Drive Electronics
IFS- Item for Sale
IRQ - Interrupt Request
ISA - Industry Standard Architecture
ISO - International Standards Organization
--- J ---
JBL - JBL (Jame B. Lansing) Speakers
JVC - JVC Company of America
- K ---
Kbps - Kilobits Per Second
KBps - KiloBytes per second
--- L ---
LG - LG Electronics
LAN - Local Are Network
LCD - Liquid Crystal Display
LDT - Lightning Data Transport
LED - Light Emitting Diode
--- M ---
MAC - Media Access Control
MB � MotherBoard or Megabyte
MBps - Megabytes Per Second
Mbps - Megabits Per Second or Megabits Per Second
MHz - MegaHertz
MIPS - Million Instructions Per Second
MMX - Multi-Media Extensions
MSI - Micro Star International
--- N ---
NAS - Network Attached Storage
NAT - Network Address Translation
NEC - NEC Corporation
NIC - Network Interface Card
--- O ---
OC - Overclock (Over Clock)
OCZ - OCZ Technology
OEM - Original Equipment Manufacturer
--- P ---
PC - Personal Computer
PCB - Printed Circuit Board
PCI - Peripheral Component Interconnect
PDA - Personal Digital Assistant
PCMCIA - Peripheral Component Microchannel Interconnect Architecture
PGA - Professional Graphics Array
PLD - Programmable Logic Device
PM - Private Message / Private Messaging
PnP - Plug 'n Play
PNY - PNY Technology
POST - Power On Self Test
PPPoA - Point-to-Point Protocol over ATM
PPPoE - Point-to-Point Protocol over Ethernet
PQI - PQI Corporation
PSU - Power Supply Unit
--- R ---
RAID - Redundant Array of Inexpensive Disks
RAM - Random Access Memory
RAMDAC - Random Access Memory Digital Analog Convertor
RDRAM - Rambus Dynamic Random Access Memory
ROM - Read Only Memory
RPM - Revolutions Per Minute
--- S ---
SASID - Self-scanned Amorphous Silicon Integrated Display
SCA - SCSI Configured Automatically
SCSI - Small Computer System Interface
SDRAM - Synchronous Dynamic Random Access Memory
SECC - Single Edge Contact Connector
SODIMM - Small Outline Dual Inline Memory Module
SPARC - Scalable Processor ArChitecture
SOHO - Small Office Home Office
SRAM - Static Random Access Memory
SSE - Streaming SIMD Extensions
SVGA - Super Video Graphics Array
S/PDIF - Sony/Philips Digital Interface
--- T ---
TB - Terabytes
TBps - Terabytes per second
Tbps - Terabits per second
TDK - TDK Electronics
TEC - Thermoelectric Cooler
TPC - TipidPC
TWAIN - Technology Without An Important Name
--- U ---
UART - Universal Asynchronous Receiver/Transmitter
USB - Universal Serial Bus
UTP - Unshieled Twisted Pair
--- V ---
VCD - Video CD
VPN - Virtual Private Network
--- W ---
WAN - Wide Area Network
WTB - Want to Buy
WYSIWYG - What You See Is What You Get
--- X ---
XGA - Extended Graphics Array
XFX - XFX Graphics, a Division of Pine
XMS - Extended Memory Specification
XT - Extended Technology
AGP - Accelerated Graphics Port
ALI - Acer Labs, Incorporated
ALU - Arithmetic Logic Unit
AMD - Advanced Micro Devices
APC - American Power Conversion
ASCII - American Standard Code for Information Interchange
ASIC - Application Specific Integrated Circuit
ASPI - Advanced SCSI Programming Interface
AT - Advanced Technology
ATI - ATI Technologies Inc.
ATX - Advanced Technology Extended
--- B ---BFG - BFG Technologies
BIOS - Basic Input Output System
BNC - Barrel Nut Connector
--- C ---
CAS - Column Address Signal
CD - Compact Disk
CDR - Compact Disk Recorder
CDRW - Compact Disk Re-Writer
CD-ROM - Compact Disk - Read Only Memory
CFM - Cubic Feet per Minute (ft�/min)
CMOS - Complementary Metal Oxide Semiconductor
CPU - Central Processing Unit
CTX - CTX Technology Corporation (Commited to Excellence)
--- D ---
DDR - Double Data Rate
DDR-SDRAM - Double Data Rate - Synchronous Dynamic Random Access Memory
DFI - DFI Inc. (Design for Innovation)
DIMM - Dual Inline Memory Module
DRAM - Dynamic Random Access Memory
DPI - Dots Per Inch
DSL - See ASDL
DVD - Digital Versatile Disc
DVD-RAM - Digital Versatile Disk - Random Access Memory
--- E ---
ECC - Error Correction Code
ECS - Elitegroup Computer Systems
EDO - Extended Data Out
EEPROM - Electrically Erasable Programmable Read-Only Memory
EPROM - Erasable Programmable Read-Only Memory
EVGA - EVGA Corporation
--- F ---
FC-PGA - Flip Chip Pin Grid Array
FDC - Floppy Disk Controller
FDD - Floppy Disk Drive
FPS - Frame Per Second
FPU - Floating Point Unit
FSAA - Full Screen Anti-Aliasing
FS - For Sale
FSB - Front Side Bus
--- G ---
GB - Gigabytes
GBps - Gigabytes per second or Gigabits per second
GDI - Graphical Device Interface
GHz - GigaHertz
--- H ---
HDD - Hard Disk Drive
HIS - Hightech Information System Limited
HP - Hewlett-Packard Development Company
HSF - Heatsink-Fan
--- I ---
IBM - International Business Machines Corporation
IC - Integrated Circuit
IDE - Integrated Drive Electronics
IFS- Item for Sale
IRQ - Interrupt Request
ISA - Industry Standard Architecture
ISO - International Standards Organization
--- J ---
JBL - JBL (Jame B. Lansing) Speakers
JVC - JVC Company of America
- K ---
Kbps - Kilobits Per Second
KBps - KiloBytes per second
--- L ---
LG - LG Electronics
LAN - Local Are Network
LCD - Liquid Crystal Display
LDT - Lightning Data Transport
LED - Light Emitting Diode
--- M ---
MAC - Media Access Control
MB � MotherBoard or Megabyte
MBps - Megabytes Per Second
Mbps - Megabits Per Second or Megabits Per Second
MHz - MegaHertz
MIPS - Million Instructions Per Second
MMX - Multi-Media Extensions
MSI - Micro Star International
--- N ---
NAS - Network Attached Storage
NAT - Network Address Translation
NEC - NEC Corporation
NIC - Network Interface Card
--- O ---
OC - Overclock (Over Clock)
OCZ - OCZ Technology
OEM - Original Equipment Manufacturer
--- P ---
PC - Personal Computer
PCB - Printed Circuit Board
PCI - Peripheral Component Interconnect
PDA - Personal Digital Assistant
PCMCIA - Peripheral Component Microchannel Interconnect Architecture
PGA - Professional Graphics Array
PLD - Programmable Logic Device
PM - Private Message / Private Messaging
PnP - Plug 'n Play
PNY - PNY Technology
POST - Power On Self Test
PPPoA - Point-to-Point Protocol over ATM
PPPoE - Point-to-Point Protocol over Ethernet
PQI - PQI Corporation
PSU - Power Supply Unit
--- R ---
RAID - Redundant Array of Inexpensive Disks
RAM - Random Access Memory
RAMDAC - Random Access Memory Digital Analog Convertor
RDRAM - Rambus Dynamic Random Access Memory
ROM - Read Only Memory
RPM - Revolutions Per Minute
--- S ---
SASID - Self-scanned Amorphous Silicon Integrated Display
SCA - SCSI Configured Automatically
SCSI - Small Computer System Interface
SDRAM - Synchronous Dynamic Random Access Memory
SECC - Single Edge Contact Connector
SODIMM - Small Outline Dual Inline Memory Module
SPARC - Scalable Processor ArChitecture
SOHO - Small Office Home Office
SRAM - Static Random Access Memory
SSE - Streaming SIMD Extensions
SVGA - Super Video Graphics Array
S/PDIF - Sony/Philips Digital Interface
--- T ---
TB - Terabytes
TBps - Terabytes per second
Tbps - Terabits per second
TDK - TDK Electronics
TEC - Thermoelectric Cooler
TPC - TipidPC
TWAIN - Technology Without An Important Name
--- U ---
UART - Universal Asynchronous Receiver/Transmitter
USB - Universal Serial Bus
UTP - Unshieled Twisted Pair
--- V ---
VCD - Video CD
VPN - Virtual Private Network
--- W ---
WAN - Wide Area Network
WTB - Want to Buy
WYSIWYG - What You See Is What You Get
--- X ---
XGA - Extended Graphics Array
XFX - XFX Graphics, a Division of Pine
XMS - Extended Memory Specification
XT - Extended Technology
Best Keyboard Shortcuts
Getting used to using your keyboard exclusively and leaving your mouse behind will make you much more efficient at performing any task on any Windows system. I use the following keyboard shortcuts every day:
Windows key + R = Run menu
This is usually followed by:
cmd = Command Prompt
iexplore + "web address" = Internet Explorer
compmgmt.msc = Computer Management
dhcpmgmt.msc = DHCP Management
dnsmgmt.msc = DNS Management
services.msc = Services
eventvwr = Event Viewer
dsa.msc = Active Directory Users and Computers
dssite.msc = Active Directory Sites and Services
Windows key + E = Explorer
ALT + Tab = Switch between windows
ALT, Space, X = Maximize window
CTRL + Shift + Esc = Task Manager
Windows key + Break = System properties
Windows key + F = Search
Windows key + D = Hide/Display all windows
CTRL + C = copy
CTRL + X = cut
CTRL + V = paste
Also don't forget about the "Right-click" key next to the right Windows key on your keyboard. Using the arrows and that key can get just about anything done once you've opened up any program.
Keyboard Shortcuts
[Alt] and [Esc] Switch between running applications
[Alt] and letter Select menu item by underlined letter
[Ctrl] and [Esc] Open Program Menu
[Ctrl] and [F4] Close active document or group windows (does not work with some applications)
[Alt] and [F4] Quit active application or close current window
[Alt] and [-] Open Control menu for active document
Ctrl] Lft., Rt. arrow Move cursor forward or back one word
Ctrl] Up, Down arrow Move cursor forward or back one paragraph
[F1] Open Help for active application
Windows+M Minimize all open windows
Shift+Windows+M Undo minimize all open windows
Windows+F1 Open Windows Help
Windows+Tab Cycle through the Taskbar buttons
Windows+Break Open the System Properties dialog box
acessability shortcuts
Right SHIFT for eight seconds........ Switch FilterKeys on and off.
Left ALT +left SHIFT +PRINT SCREEN....... Switch High Contrast on and off.
Left ALT +left SHIFT +NUM LOCK....... Switch MouseKeys on and off.
SHIFT....... five times Switch StickyKeys on and off.
NUM LOCK...... for five seconds Switch ToggleKeys on and off.
explorer shortcuts
END....... Display the bottom of the active window.
HOME....... Display the top of the active window.
NUM LOCK+ASTERISK....... on numeric keypad (*) Display all subfolders under the selected folder.
NUM LOCK+PLUS SIGN....... on numeric keypad (+) Display the contents of the selected folder.
NUM LOCK+MINUS SIGN....... on numeric keypad (-) Collapse the selected folder.
LEFT ARROW...... Collapse current selection if it's expanded, or select parent folder.
RIGHT ARROW....... Display current selection if it's collapsed, or select first subfolder.
Type the following commands in your Run Box (Windows Key + R) or Start Run
devmgmt.msc = Device Manager
msinfo32 = System Information
cleanmgr = Disk Cleanup
ntbackup = Backup or Restore Wizard (Windows Backup Utility)
mmc = Microsoft Management Console
excel = Microsoft Excel (If Installed)
msaccess = Microsoft Access (If Installed)
powerpnt = Microsoft PowerPoint (If Installed)
winword = Microsoft Word (If Installed)
frontpg = Microsoft FrontPage (If Installed)
notepad = Notepad
wordpad = WordPad
calc = Calculator
msmsgs = Windows Messenger
mspaint = Microsoft Paint
wmplayer = Windows Media Player
rstrui = System Restore
netscp6 = Netscape 6.x
netscp = Netscape 7.x
netscape = Netscape 4.x
waol = America Online
control = Opens the Control Panel
control printers = Opens the Printers Dialog
internetbrowser
type in u're adress "google", then press [Right CTRL] and [Enter]
add www. and .com to word and go to it
For Windows XP:
Copy. CTRL+C
Cut. CTRL+X
Paste. CTRL+V
Undo. CTRL+Z
Delete. DELETE
Delete selected item permanently without placing the item in the Recycle Bin. SHIFT+DELETE
Copy selected item. CTRL while dragging an item
Create shortcut to selected item. CTRL+SHIFT while dragging an item
Rename selected item. F2
Move the insertion point to the beginning of the next word. CTRL+RIGHT ARROW
Move the insertion point to the beginning of the previous word. CTRL+LEFT ARROW
Move the insertion point to the beginning of the next paragraph. CTRL+DOWN ARROW
Move the insertion point to the beginning of the previous paragraph. CTRL+UP ARROW
Highlight a block of text. CTRL+SHIFT with any of the arrow keys
Select more than one item in a window or on the desktop, or select text within a document. SHIFT with any of the arrow keys
Select all. CTRL+A
Search for a file or folder. F3
View properties for the selected item. ALT+ENTER
Close the active item, or quit the active program. ALT+F4
Opens the shortcut menu for the active window. ALT+SPACEBAR
Close the active document in programs that allow you to have multiple documents open simultaneously. CTRL+F4
Switch between open items. ALT+TAB
Cycle through items in the order they were opened. ALT+ESC
Cycle through screen elements in a window or on the desktop. F6
Display the Address bar list in My Computer or Windows Explorer. F4
Display the shortcut menu for the selected item. SHIFT+F10
Display the System menu for the active window. ALT+SPACEBAR
Display the Start menu. CTRL+ESC
Display the corresponding menu. ALT+Underlined letter in a menu name
Carry out the corresponding command. Underlined letter in a command name on an open menu
Activate the menu bar in the active program. F10
Open the next menu to the right, or open a submenu. RIGHT ARROW
Open the next menu to the left, or close a submenu. LEFT ARROW
Refresh the active window. F5
View the folder one level up in My Computer or Windows Explorer. BACKSPACE
Cancel the current task. ESC
SHIFT when you insert a CD into the CD-ROM drive Prevent the CD from automatically playing.
Use these keyboard shortcuts for dialog boxes:
To Press
Move forward through tabs. CTRL+TAB
Move backward through tabs. CTRL+SHIFT+TAB
Move forward through options. TAB
Move backward through options. SHIFT+TAB
Carry out the corresponding command or select the corresponding option. ALT+Underlined letter
Carry out the command for the active option or button. ENTER
Select or clear the check box if the active option is a check box. SPACEBAR
Select a button if the active option is a group of option buttons. Arrow keys
Display Help. F1
Display the items in the active list. F4
Open a folder one level up if a folder is selected in the Save As or Open dialog box. BACKSPACE
If you have a Microsoft Natural Keyboard, or any other compatible keyboard that includes the Windows logo key and the Application key , you can use these keyboard shortcuts:
Display or hide the Start menu. WIN Key
Display the System Properties dialog box. WIN Key+BREAK
Show the desktop. WIN Key+D
Minimize all windows. WIN Key+M
Restores minimized windows. WIN Key+Shift+M
Open My Computer. WIN Key+E
Search for a file or folder. WIN Key+F
Search for computers. CTRL+WIN Key+F
Display Windows Help. WIN Key+F1
Lock your computer if you are connected to a network domain, or switch users if you are not connected to a network domain. WIN Key+ L
Open the Run dialog box. WIN Key+R
Open Utility Manager. WIN Key+U
accessibility keyboard shortcuts:
Switch FilterKeys on and off. Right SHIFT for eight seconds
Switch High Contrast on and off. Left ALT+left SHIFT+PRINT SCREEN
Switch MouseKeys on and off. Left ALT +left SHIFT +NUM LOCK
Switch StickyKeys on and off. SHIFT five times
Switch ToggleKeys on and off. NUM LOCK for five seconds
Open Utility Manager. WIN Key+U
shortcuts you can use with Windows Explorer:
Display the bottom of the active window. END
Display the top of the active window. HOME
Display all subfolders under the selected folder. NUM LOCK+ASTERISK on numeric keypad (*)
Display the contents of the selected folder. NUM LOCK+PLUS SIGN on numeric keypad (+)
Collapse the selected folder. NUM LOCK+MINUS SIGN on numeric keypad (-)
Collapse current selection if it's expanded, or select parent folder. LEFT ARROW
Display current selection if it's collapsed, or select first subfolder. RIGHT ARROW
Windows key + R = Run menu
This is usually followed by:
cmd = Command Prompt
iexplore + "web address" = Internet Explorer
compmgmt.msc = Computer Management
dhcpmgmt.msc = DHCP Management
dnsmgmt.msc = DNS Management
services.msc = Services
eventvwr = Event Viewer
dsa.msc = Active Directory Users and Computers
dssite.msc = Active Directory Sites and Services
Windows key + E = Explorer
ALT + Tab = Switch between windows
ALT, Space, X = Maximize window
CTRL + Shift + Esc = Task Manager
Windows key + Break = System properties
Windows key + F = Search
Windows key + D = Hide/Display all windows
CTRL + C = copy
CTRL + X = cut
CTRL + V = paste
Also don't forget about the "Right-click" key next to the right Windows key on your keyboard. Using the arrows and that key can get just about anything done once you've opened up any program.
Keyboard Shortcuts
[Alt] and [Esc] Switch between running applications
[Alt] and letter Select menu item by underlined letter
[Ctrl] and [Esc] Open Program Menu
[Ctrl] and [F4] Close active document or group windows (does not work with some applications)
[Alt] and [F4] Quit active application or close current window
[Alt] and [-] Open Control menu for active document
Ctrl] Lft., Rt. arrow Move cursor forward or back one word
Ctrl] Up, Down arrow Move cursor forward or back one paragraph
[F1] Open Help for active application
Windows+M Minimize all open windows
Shift+Windows+M Undo minimize all open windows
Windows+F1 Open Windows Help
Windows+Tab Cycle through the Taskbar buttons
Windows+Break Open the System Properties dialog box
acessability shortcuts
Right SHIFT for eight seconds........ Switch FilterKeys on and off.
Left ALT +left SHIFT +PRINT SCREEN....... Switch High Contrast on and off.
Left ALT +left SHIFT +NUM LOCK....... Switch MouseKeys on and off.
SHIFT....... five times Switch StickyKeys on and off.
NUM LOCK...... for five seconds Switch ToggleKeys on and off.
explorer shortcuts
END....... Display the bottom of the active window.
HOME....... Display the top of the active window.
NUM LOCK+ASTERISK....... on numeric keypad (*) Display all subfolders under the selected folder.
NUM LOCK+PLUS SIGN....... on numeric keypad (+) Display the contents of the selected folder.
NUM LOCK+MINUS SIGN....... on numeric keypad (-) Collapse the selected folder.
LEFT ARROW...... Collapse current selection if it's expanded, or select parent folder.
RIGHT ARROW....... Display current selection if it's collapsed, or select first subfolder.
Type the following commands in your Run Box (Windows Key + R) or Start Run
devmgmt.msc = Device Manager
msinfo32 = System Information
cleanmgr = Disk Cleanup
ntbackup = Backup or Restore Wizard (Windows Backup Utility)
mmc = Microsoft Management Console
excel = Microsoft Excel (If Installed)
msaccess = Microsoft Access (If Installed)
powerpnt = Microsoft PowerPoint (If Installed)
winword = Microsoft Word (If Installed)
frontpg = Microsoft FrontPage (If Installed)
notepad = Notepad
wordpad = WordPad
calc = Calculator
msmsgs = Windows Messenger
mspaint = Microsoft Paint
wmplayer = Windows Media Player
rstrui = System Restore
netscp6 = Netscape 6.x
netscp = Netscape 7.x
netscape = Netscape 4.x
waol = America Online
control = Opens the Control Panel
control printers = Opens the Printers Dialog
internetbrowser
type in u're adress "google", then press [Right CTRL] and [Enter]
add www. and .com to word and go to it
For Windows XP:
Copy. CTRL+C
Cut. CTRL+X
Paste. CTRL+V
Undo. CTRL+Z
Delete. DELETE
Delete selected item permanently without placing the item in the Recycle Bin. SHIFT+DELETE
Copy selected item. CTRL while dragging an item
Create shortcut to selected item. CTRL+SHIFT while dragging an item
Rename selected item. F2
Move the insertion point to the beginning of the next word. CTRL+RIGHT ARROW
Move the insertion point to the beginning of the previous word. CTRL+LEFT ARROW
Move the insertion point to the beginning of the next paragraph. CTRL+DOWN ARROW
Move the insertion point to the beginning of the previous paragraph. CTRL+UP ARROW
Highlight a block of text. CTRL+SHIFT with any of the arrow keys
Select more than one item in a window or on the desktop, or select text within a document. SHIFT with any of the arrow keys
Select all. CTRL+A
Search for a file or folder. F3
View properties for the selected item. ALT+ENTER
Close the active item, or quit the active program. ALT+F4
Opens the shortcut menu for the active window. ALT+SPACEBAR
Close the active document in programs that allow you to have multiple documents open simultaneously. CTRL+F4
Switch between open items. ALT+TAB
Cycle through items in the order they were opened. ALT+ESC
Cycle through screen elements in a window or on the desktop. F6
Display the Address bar list in My Computer or Windows Explorer. F4
Display the shortcut menu for the selected item. SHIFT+F10
Display the System menu for the active window. ALT+SPACEBAR
Display the Start menu. CTRL+ESC
Display the corresponding menu. ALT+Underlined letter in a menu name
Carry out the corresponding command. Underlined letter in a command name on an open menu
Activate the menu bar in the active program. F10
Open the next menu to the right, or open a submenu. RIGHT ARROW
Open the next menu to the left, or close a submenu. LEFT ARROW
Refresh the active window. F5
View the folder one level up in My Computer or Windows Explorer. BACKSPACE
Cancel the current task. ESC
SHIFT when you insert a CD into the CD-ROM drive Prevent the CD from automatically playing.
Use these keyboard shortcuts for dialog boxes:
To Press
Move forward through tabs. CTRL+TAB
Move backward through tabs. CTRL+SHIFT+TAB
Move forward through options. TAB
Move backward through options. SHIFT+TAB
Carry out the corresponding command or select the corresponding option. ALT+Underlined letter
Carry out the command for the active option or button. ENTER
Select or clear the check box if the active option is a check box. SPACEBAR
Select a button if the active option is a group of option buttons. Arrow keys
Display Help. F1
Display the items in the active list. F4
Open a folder one level up if a folder is selected in the Save As or Open dialog box. BACKSPACE
If you have a Microsoft Natural Keyboard, or any other compatible keyboard that includes the Windows logo key and the Application key , you can use these keyboard shortcuts:
Display or hide the Start menu. WIN Key
Display the System Properties dialog box. WIN Key+BREAK
Show the desktop. WIN Key+D
Minimize all windows. WIN Key+M
Restores minimized windows. WIN Key+Shift+M
Open My Computer. WIN Key+E
Search for a file or folder. WIN Key+F
Search for computers. CTRL+WIN Key+F
Display Windows Help. WIN Key+F1
Lock your computer if you are connected to a network domain, or switch users if you are not connected to a network domain. WIN Key+ L
Open the Run dialog box. WIN Key+R
Open Utility Manager. WIN Key+U
accessibility keyboard shortcuts:
Switch FilterKeys on and off. Right SHIFT for eight seconds
Switch High Contrast on and off. Left ALT+left SHIFT+PRINT SCREEN
Switch MouseKeys on and off. Left ALT +left SHIFT +NUM LOCK
Switch StickyKeys on and off. SHIFT five times
Switch ToggleKeys on and off. NUM LOCK for five seconds
Open Utility Manager. WIN Key+U
shortcuts you can use with Windows Explorer:
Display the bottom of the active window. END
Display the top of the active window. HOME
Display all subfolders under the selected folder. NUM LOCK+ASTERISK on numeric keypad (*)
Display the contents of the selected folder. NUM LOCK+PLUS SIGN on numeric keypad (+)
Collapse the selected folder. NUM LOCK+MINUS SIGN on numeric keypad (-)
Collapse current selection if it's expanded, or select parent folder. LEFT ARROW
Display current selection if it's collapsed, or select first subfolder. RIGHT ARROW
Boot Windows XP Fast
Follow the following steps
1. Open notepad.exe, type "del c:\windows\prefetch\ntosboot-*.* /q" (without the quotes) & save as "ntosboot.bat" in c:\
2. From the Start menu, select "Run..." & type "gpedit.msc".
3. Double click "Windows Settings" under "Computer Configuration" and double click again on "Shutdown" in the right window.
4. In the new window, click "add", "Browse", locate your "ntosboot.bat" file & click "Open".
5. Click "OK", "Apply" & "OK" once again to exit.
6. From the Start menu, select "Run..." & type "devmgmt.msc".
7. Double click on "IDE ATA/ATAPI controllers"
8. Right click on "Primary IDE Channel" and select "Properties".
9. Select the "Advanced Settings" tab then on the device or 1 that doesn't have 'device type' greyed out select 'none' instead of 'autodetect' & click "OK".
10. Right click on "Secondary IDE channel", select "Properties" and repeat step 9.
11. Reboot your computer.
1. Open notepad.exe, type "del c:\windows\prefetch\ntosboot-*.* /q" (without the quotes) & save as "ntosboot.bat" in c:\
2. From the Start menu, select "Run..." & type "gpedit.msc".
3. Double click "Windows Settings" under "Computer Configuration" and double click again on "Shutdown" in the right window.
4. In the new window, click "add", "Browse", locate your "ntosboot.bat" file & click "Open".
5. Click "OK", "Apply" & "OK" once again to exit.
6. From the Start menu, select "Run..." & type "devmgmt.msc".
7. Double click on "IDE ATA/ATAPI controllers"
8. Right click on "Primary IDE Channel" and select "Properties".
9. Select the "Advanced Settings" tab then on the device or 1 that doesn't have 'device type' greyed out select 'none' instead of 'autodetect' & click "OK".
10. Right click on "Secondary IDE channel", select "Properties" and repeat step 9.
11. Reboot your computer.
add an Internet URL address bar to your Windows XP taskbar
You can add an Internet URL address bar to your Windows XP taskbar. Doing so will let you type in URLs and launch Web pages without first launching a browser. It will also let you launch some native Windows XP applications in much the same way as you would via the Run menu (so you could type in calc to launch the calculator or mspaint to launch Microsoft Paint. Here's how you add the address bar:
1. Right-click on the taskbar, select Toolbars, and then click Address.
2. The word Address will appear on your taskbar.
3. Double click it to access it.
4. If that doesn't work, your taskbar is locked. You can unlock it by right-clicking on the taskbar again and uncheck Lock the Taskbar.
NOTE: You may also need to grab the vertical dotted lines beside the word Address and drag it to the left to make the Address window appear.
1. Right-click on the taskbar, select Toolbars, and then click Address.
2. The word Address will appear on your taskbar.
3. Double click it to access it.
4. If that doesn't work, your taskbar is locked. You can unlock it by right-clicking on the taskbar again and uncheck Lock the Taskbar.
NOTE: You may also need to grab the vertical dotted lines beside the word Address and drag it to the left to make the Address window appear.
How To: Change Your Ip In Less Then 1 Minute
1. Click on "Start" in the bottom left hand corner of screen
2. Click on "Run"
3. Type in "command" and hit ok
You should now be at an MSDOS prompt screen.
4. Type "ipconfig /release" just like that, and hit "enter"5. Type "exit" and leave the prompt
6. Right-click on "Network Places" or "My Network Places" on your desktop.
7. Click on "properties"
You should now be on a screen with something titled "Local Area Connection", or something close to that, and, if you have a network hooked up, all of your other networks.
8. Right click on "Local Area Connection" and click "properties"
9. Double-click on the "Internet Protocol (TCP/IP)" from the list under the "General" tab
10. Click on "Use the following IP address" under the "General" tab
11. Create an IP address (It doesn't matter what it is. I just type 1 and 2 until i fill the area up).
12. Press "Tab" and it should automatically fill in the "Subnet Mask" section with default numbers.
13. Hit the "Ok" button here
14. Hit the "Ok" button again
You should now be back to the "Local Area Connection" screen.
15. Right-click back on "Local Area Connection" and go to properties again.
16. Go back to the "TCP/IP" settings
17. This time, select "Obtain an IP address automatically"tongue.gif 18. Hit "Ok"19. Hit "Ok" again
20. You now have a new IP address
With a little practice, you can easily get this process down to 15 seconds.
P.S:
This only changes your dynamic IP address, not your ISP/IP address.
2. Click on "Run"
3. Type in "command" and hit ok
You should now be at an MSDOS prompt screen.
4. Type "ipconfig /release" just like that, and hit "enter"5. Type "exit" and leave the prompt
6. Right-click on "Network Places" or "My Network Places" on your desktop.
7. Click on "properties"
You should now be on a screen with something titled "Local Area Connection", or something close to that, and, if you have a network hooked up, all of your other networks.
8. Right click on "Local Area Connection" and click "properties"
9. Double-click on the "Internet Protocol (TCP/IP)" from the list under the "General" tab
10. Click on "Use the following IP address" under the "General" tab
11. Create an IP address (It doesn't matter what it is. I just type 1 and 2 until i fill the area up).
12. Press "Tab" and it should automatically fill in the "Subnet Mask" section with default numbers.
13. Hit the "Ok" button here
14. Hit the "Ok" button again
You should now be back to the "Local Area Connection" screen.
15. Right-click back on "Local Area Connection" and go to properties again.
16. Go back to the "TCP/IP" settings
17. This time, select "Obtain an IP address automatically"tongue.gif 18. Hit "Ok"19. Hit "Ok" again
20. You now have a new IP address
With a little practice, you can easily get this process down to 15 seconds.
P.S:
This only changes your dynamic IP address, not your ISP/IP address.
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