Question

how to add data after last line for multiple files in unix

Answer 1

General Introduction

The vi editor (short for visual editor) is a screen editor which is available on almost all Unix systems. Once you have learned vi, you will find that it is a fast and powerful editor. vi has no menus but instead uses combinations of keystrokes in order to accomplish commands. If you are just beginning to learn Unix, you might find the Pico editor easier to use (most command options are displayed at the bottom of the screen). If you use the Pine email application and have composed or replied to a message you have probably already used Pico as it is used for text entry. For more information please refer to the Pine/Pico page.

Starting vi

To start using vi, at the Unix prompt type vi followed by a file name. If you wish to edit an existing file, type in its name; if you are creating a new file, type in the name you wish to give to the new file.

%vi filename

Then hit Return. You will see a screen similar to the one below which shows blank lines with tildes and the name and status of the file.

~

~

"myfile" [New file]

vi's Modes and Moods

vi has two modes: the command mode and the insert mode. It is essential that you know which mode you are in at any given point in time. When you are in command mode, letters of the keyboard will be interpreted as commands. When you are in insert mode the same letters of the keyboard will type or edit text. vi always starts out in command mode. When you wish to move between the two modes, keep these things in mind. You can type i to enter the insert mode. If you wish to leave insert mode and return to the command mode, hit the ESC key. If you're not sure where you are, hit ESCa couple of times and that should put you back in command mode.

General Command Information

As mentioned previously, vi uses letters as commands. It is important to note that in general vi commands:are case sensitive - lowercase and uppercase command letters do different thingsare not displayed on the screen when you type themgenerally do not require a Returnafter you type the command.You will see some commands which start with a colon (:). These commands are ex commands which are used by the ex editor. ex is the true editor which lies underneath vi -- in other words, vi is the interface for the ex editor.

Entering Text

To begin entering text in an empty file, you must first change from the command mode to the insert mode. To do this, type the letter i. When you start typing, anything you type will be entered into the file. Type a few short lines and hit Return at the end of each of line. Unlike word processors, vi does not use word wrap. It will break a line at the edge of the screen. If you make a mistake, you can use the Backspace key to remove your errors. If the Backspace key doesn't work properly on your system, try using the Ctrl h key combination.

Cursor Movement

You must be in command mode if you wish to move the cursor to another position in your file. If you've just finished typing text, you're still in insert mode and will need to press ESCto return to the command mode.

Moving One Character at a Time

Try using your direction keys to move up, down, left and right in your file. Sometimes, you may find that the direction keys don't work. If that is the case, to move the cursor one character at the time, you may use the h, j, k, and l keys. These keys move you in the following directions:h left one space l right one space j down one space k up one spaceIf you move the cursor as far as you can in any direction, you may see a screen flash or hear a beep.

Moving among Words and Lines

While these four keys (or your direction keys) can move you just about anywhere you want to go in your file, there are some shortcut keys that you can use to move a little more quickly through a document. To move more quickly among words, you might use the following:w moves the cursor forward one word b moves the cursor backward one word (if in the middle of a word, b will move you to the beginning of the current word). e moves to the end of a word.To build on this further, you can precede these commands with a number for greater movement. For example, 5w would move you forward five words; 12b would move you backwards twelve words. [You can also use numbers with the commands mentioned earlier. For example, 5j would move you down 5 characters.]

Command Keys and Case

You will find when using vi that lower case and upper case command keys are interpreted differently. For example, when using the lower case w, b, and ecommands, words will be defined by a space or a punctuation mark. On the other hand, W, B, and E commands may be used to move between words also, but these commands ignore punctuation.

Shortcuts

Two short cuts for moving quickly on a line include the $ and the 0 (zero) keys. The $ key will move you to the end of a line, while the 0 will move you quickly to the beginning of a line.