Archive for the ‘Programming’ Category

Characteristics of X utility in Unix and Linux

January 10, 2019 Comments off

X11 enables Unix and Linux desktop and graphical user Interface. You can use all GUI facility and mouse using the X server.

unix linux programmingThe X version number X11 refers to the protocol, and the version number changes when the protocol changes. The new version becomes incompatible with the old version and existing programs will no longer work. For this reason, I don’t think there will be a version 12, because that would require too much conversion of existing software. But that does not mean that X cannot change and add new functions.

Every so often MIT releases a collection of sample programs and programming libraries; these represent the release level. New releases might contain bug fixes, performance improvements, and improvement or enhancements to programming libraries.

The original designers of X went out of their way to ensure that X would never be limiting. An extension mechanism allows new features to be built into the server without producing a performance penalty. In fact, extensions are often used by system manufacturers to take advantage of hardware features. They are also used by the X Consortium to implement and agree on new features.

Even with the wide acceptance of X11, new developments continue. Works in progress include extensions to support various input devices, X for Japanese use, a multithreaded X server, and 3-D graphics.

Other interesting developments on the GUI front concern the evolution of the graphical desktop, a screen-based metaphor for a real desktop that contains icons representing applications and other accessories. The X utility bundled with Solaris, Linux, and HP’s UX are all good examples. The only question is, can these desktop managers replace the shell command line, and will the evolution of the desktop give rise to the same kind of religious wars we have endured between the C shell and the Korn shell.

In a graphical user interface, applications execute in windows, using a consistent set of menus and dialog boxes, along with other graphical elements such as scroll bars and icons. Instead of typing commands at the prompt, you use a mouse, trackball, or their pointing device to point to pictorial elements on the screen, then click, double-click, or drag one of the mouse buttons to make the desired action occur.

The Fundamental idea behind using a windowing system with a consistent look and feel is that you do not have to learn new commands when you move to a new application. Instead, you take advantage of habit to perform similar tasks. You know that you will always find the Open command in the File menu, and the Resize command in the Window menu.


What is Directory Permissions of Linux and Unix

January 7, 2019 Comments off

linux permissionThe Three permissions can also be applied to directories, although the meanings of reading, write and execute have to be interpreted slightly differently. I’ll explain these subtle differences in several ways to ensure that you understand their significance.

Read and write directory permissions are fairly obvious. You need read permission to determine the contents of a directory with ls or a similar command. ls has to read the various fields in a directory in order to give you the names of its files and subdirectories. Directory read permission is quite independent of, and must not be confused with, any of the permissions set on the files and subdirectories themselves. If you grant others read permission on your directory, but withhold read/write permissions on your files, then other users will be able to see all your filenames but will be unable to read or change the contents of your files. Conversely, you could (in theory) withhold directory read permission but grant file read and/or write permissions. If so, other users would not be able to determine your filenames with ls, yet if they somehow managed to learn the name of one of your files, they might be able to read and/or change it.

Directory writes permission lets you alter the contents of a directory. Without such permission, therefore, you cannot add or remove files or subdirectories.

Directories execute permission is not the same as files execute permission. While file executes permission lets you run a file, directory executes permission is often called directory search permission. This permission allows a user to access any file or subdirectory since such access calls for a search of the directory in order to locate that file or subdirectory.

In order to cd into a directory, you also need the directory to execute permission in that directory; and even with this permission, you would further require write permission in that directory in order to alter its contents, that is, create and erase files, or create and erase its subdirectories.

Stan was able to create the subdirectory memo and create and access files therein because he has read, write, and execute permissions in his own home directory,/ usr/ stan, and its children. Yes, each user acquires these and similar permissions on their own directories and files as a sort of birthright, and only root one takes them away. (You, as the owner, could also remove some of all of these permissions from yourself, or even relinquish your ownership, but that might border on the suicidal).

Whether you have permission to cd into /usr/may, for example, is entirely up to may and root, since only they can change the permissions of Mary’s files and directories.

Mary may well grant group members and others execute permission on her home directory but withhold other permissions. If so, such users could cd to /usr/mary, but without directory write permission, would not be free to create files and subdirectories there. Stan could not even list the files in /usr/mary unless Mary grants him directory read permission there. Note that if you happened to know the name of a program file in /usr/mary and she gave you execute permissions on both directory and the program, you could run it without needing directory read permission. If you find this confusing, be patient. All will be clear soon.

What is Menu Editor in Visual Basic?

March 11, 2014 Comments off

What is Menu Editor in Visual Basic?

Menu Editor utility of VB can be accessed from tools menu in the forms design screen. This utility is used for creating menus. It allows you to create custom menus for your application and to define their properties.

Dialog Box Options:

Caption: Allows you to enter the menu or command name that you want to appear on your menu bar or in a menu. If you want to create a separator bar in your menu, you can type a single hyphen (-) in the Caption box.

To give the user keyboard access to a menu item, insert an ampersand (&) before a letter. At run time, this is underlined (the ampersand is not visible), and the user can access the menu or command by pressing ALT and the letter. If you need an ampersand to show in the menu, put two consecutive ampersands in the caption.

Name: Allows you to enter a control name for the menu item. A control name is an identifier used only to access the menu item in code; it does not appear in a menu.

Index: Allows you to assign a numeric value that determines the control’s position within a control array. This position is not related to the screen position.

Shortcut: Allows you to select a shortcut key for each command.

HelpContextID: Allows you to assign a unique numeric value for the context ID. This value is used to find the appropriate Help topic in the help file identified by the HelpFile property.

NegotiatePosition: Allows you to select the menu’s NegotiatePosition property. This property determines whether and how the menu appears in a container form.

Checked: Allows you to have a check mark appear initially at the left of a menu item. It is generally used to indicate whether a toggle option is turned on or off.

Enabled: Allows you to select whether you want the menu item to respond to events, or clear if you want the item to be unavailable and appear dimmed.

Visible: Allows you to have the menu item appear on the menu.

WindowsList: Determines if the menu control contains a list of open MDI child forms in an MDI application.

Right Arrow: Moves the selected menu down one level each time you click it. You can create up to four levels of submenus.

Left Arrow: Moves the selected menu up one level each time you click it. You can create up to four levels of submenus.

Up Arrow: Moves the selected menu item up one position within the same menu level each time you click it.

Down Arrow: Moves the selected menu item down one position within the same menu level each time you click it.

Menu List: A list box that displays a hierarchical list of menu items. Submenu items are indented to indicate their hierarchical position of level.

Next: Moves selection to the next line.

Insert: Inserts a line in the list box above the currently selected line.

Delete: Deletes the currently selected line.

OK: Closes the Menu Editor and applies all changes to the last form you selected. The menu is available at design time, but selecting a menu at design time opens the Code windows for that menu’s Click event rather than executing any event code.

Cancel: Closes the Menu Editor and cancels all changes.

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Learn About Visual Basic Window Adjustment

January 12, 2013 Comments off

Yesterday I read about VB windows adjustment. Off course, I am beginner in VB but it is really interesting to share some idea about this.

An immediate window enables you to debug your VisualBasic program. When you design your user interface, you use the toolbox to draw objects on a form. After you have drawn your object, the step is to customize the appearance of each object by using the properties window. Finally, after you are happy with the way your program’s user interface looks, you can define the location of the interface on the screen by using the form layout window.

How to Closing and Opening Windows in VB?

The VisualBasic user interface may seem cluttered to you, so do not be afraid to modify it for your convenience. Because most parts of the VisualBasic user interface consist of windows, you may want to close them to give yourself more screen space. Then you need to use the interface windows again, just open them up.

To close a window in the VB user interface, click in the close box of the window you want back again. To open a window and make it appear in the VB user interface choose view and then click on the window you want to open, such as code or properties windows.

How to Resizing and moving your Windows?

Rather that closes a window and makes it disappear completely, you may prefer to resize or rearrange the window instead.

To resize a window move the cursor over the edge of the Window until the cursor turns into a double-headed arrow. Then hold down the left mouse button, drag the mouse, and release the left mouse button when the window has the shape you want the window to be.

To move a window, move the cursor over the title bar of a window, hold down the left mouse button, and drag the mouse and then release the left mouse button when the window is in the desired location.

Now we are capable to adjust windows and sizing concept too. Oracle database supports VB frontend. Remote DBA support team always provides support for Oracle databases.

Visual Basic Tutorials – How to Start New Program?

December 10, 2012 Comments off

What are Options of Project of Visual Basic?

visual basic tutorialsAfter starting Microsoft VisualBasic, you have to create new project dialog box, you have a number of template of the different types of programs you want to create.

Standard Exe:

You can create a stand-alone program that you can copy, give away, or sell to others. Examples of stand-alone programs are Microsoft Word, Lotus, and Netscape Navigator. Stand alone programs have an .exe file extension.

Active X DLL:

You can create a file that has a .DLL file extension. ActiveX DLL files are not meant to be used by them. Instead, these types of files contain subprograms designed to be used as building blocks when creating a stand-alone program.

ActiveX EXE:

You can create a file that has an .EXE file extension. Unlike a standalone exe file, an ActiveX exe file is designed to work as an OLE server, which is nothing more than a program designed to share information with another program.

ActiveX Control:

You can create a file that has an .OCX file extension. Unlike an ActiveX DLL or ActiveX EXE file, an ActiveX control usually provides both subprograms and an user interface that you can reuse in other programs.

ActiveX Document DLL:

You can create a file with a .DLL file extension. An Active X document DLL file is designed to help you run programs on a web site.

ActiveX Document EXE:

You can create a file that has as .EXE file extension. An ActiveX Document EXE file can display a VisualBasic form within an internet web browser.


This feature enables you to create an Addln program specially designed to work with the VisualBasic user interface.

VB Application Wizard:

The Visual Basic friendly guide is to help you create a skeleton VisualBasic stand-alone EXE program quickly and easily.

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