Vi editor guide how to use command

Hi All,
Critical to a Linux administrator is knowledge of one or more text editors to manage the many configuration files on a Linux system. The Linux file system hierarchy organizes hardware, drivers, directories, and of course, files. You need to master a number of basic commands to manage Linux. Printer configuration can be a complex topic. Shell scripts enable you to automate many everyday processes. Security is now a huge issue that Linux can handle better than other operating systems; locally, and on larger networks such as the Internet.

The VIsual Editor

Linux and Unix are managed through a series of text files. Linux administrators do not normally use graphical editors to manage these configuration files. Editors such as WordPerfect, starOffice, and yes, even Microsoft Word normally save files in a binary format that Linux can't read. Popular text editors for Linux configuration files include emacs, pico, joe, and vi.
While emacs may be the most popular text editor in the world of Linux, every administrator needs at least a basic knowledge of vi. While emacs may be more popular and flexible, vi may help you save a broken system. If you ever have to restore a critical configuration file using an emergency boot floppy, vi is probably the only editor that you’ll have available. You need to know how to restore your system from a rescue floppy, which does not have enough room to carry any editor other than vi.So should know how to use vi editor.

$ vi /tmp/test
If this is a new file, you should see something similar to the following:
~
~
~
~
~
“/tmp/test” [New File]

The box at the top represents where your cursor is. The bottom line keeps you informed about what is going on with your editing (here you just opened a new file). In between, there are tildes (~) as filler because there is no text in the file yet. Now here's the intimidating part: There are no hints, menus, or icons to tell you what to do. On top of that, you can't just start typing. If you do, the computer is likely to beep at you. And some people complain that Linux isn't friendly.
The first things you need to know are the different operating modes: command and input. The vi editor always starts in command mode. Before you can add or change text in the file, you have to type a command (one or two letters and an optional number) to tell vi what you want to do. Case is important, so use uppercase and lowercase exactly as shown in the examples! To get into input mode, type an input command. To start out, type either of the following:

• a-The add command. After it, you can input text that starts to the right of the cursor.
• i-The insert command. After it, you can input text that starts to the left of the cursor.

Type a few words and then press Enter. Repeat that a few times until you have a few lines of text. When you’re finished typing, press Esc to return to command mode. Now that you have a file with some text in it, try moving around in your text with the following keys or letters: Remember the Esc key! It always places you back into command mode.
Arrow keys-Move the cursor up, down, left, or right in the file one character at a time. To move left and right you can also use Backspace and the space bar, respectively. If you prefer to keep your fingers on the keyboard, move the cursor with h (left), l (right), j (down), or k (up).

• w-Moves the cursor to the beginning of the next word.
• b-Moves the cursor to the beginning of the previous word.
• 0 (zero)-Moves the cursor to the beginning of the current line.
• $-Moves the cursor to the end of the current line.
• H-Moves the cursor to the upper-left corner of the screen (first line on the screen).
• M-Moves the cursor to the first character of the middle line on the screen.
• L-Moves the cursor to the lower-left corner of the screen (last line on the screen).

The only other editing you need to know is how to delete text. Here are few vi commands for deleting text:

• x-Deletes the character under the cursor.
• X-Deletes the character directly before the cursor.
• dw-Deletes from the current character to the end of the current word.
• d$-Deletes from the current character to the end of the current line.
• d0-Deletes from the previous character to the beginning of the current line.

To wrap things up, use the following keystrokes for saving and quitting the file:

• ZZ-Save the current changes to the file and exit from vi.
• :w-Save the current file but continue editing.
• :wq-Same as ZZ.
• :q-Quit the current file. This works only if you don’t have any unsaved changes.
• :q!-Quit the current file and don’t save the changes you just made to the file.

If you've really trashed the file by mistake, the :q! command is the best way to exit and abandon your changes.

The file reverts to the most recently changed version. So, if you just did a :w, you are stuck with the changes up to that point. If you just want to undo a few bad edits, press u to back out of changes.
You have learned a few vi editing commands. I describe more commands in the following sections. First, however,
here are a few tips to smooth out your first trials with vi:

• Esc-Remember that Esc gets you back to command mode. (I’ve watched people press every key on the keyboard trying to get out of a file.) Esc followed by ZZ gets you out of command mode, saves the file, and exits.
• u-Press u to undo the previous change you made. Continue to press u to undo the change before that, and the one before that.
• Ctrl+R-If you decide you didn’t want to undo the previous command, use Ctrl+R for Redo. Essentially, this command undoes your undo.
• Caps Lock-Beware of hitting Caps Lock by mistake. Everything you type in vi has a different meaning when the letters are capitalized. You don’t get a warning that you are typing capitals-things just start acting weird.
• :! command-You can run a command while you are in vi using :! followed by a command name. For example,
• type :!date to see the current date and time,
• type :!pwd to see what your current directory is,
• type :!jobs to see if you have any jobs running in the background.
• INSERT-When you are in insert mode, the word INSERT appears at the bottom of the screen.
• Ctrl+G-If you forget what you are editing, pressing these keys displays the name of the file that you are editing and the current line that you are on at the bottom of the screen. It also displays the total number of lines in the file, the percentage of how far you are through the file, and the column number the cursor is on.

Moving Around the File

Besides the few movement commands described earlier, there are other ways of moving around a vi file. To try these out, open a large file that you can’t do much damage to. (Try copying /var/log/ messages to /tmp and opening it in vi.) Here are some movement commands you can use:

• Ctrl+F-Page ahead, one page at a time.
• Ctrl+B-Page back, one page at a time.
• Ctrl+D-Page ahead one-half page at a time.
• Ctrl+U-Page back one-half page at a time.
• G-Goto the last line of the file.
• 1G-Go to the first line of the file. (Use any number to go to that line in the file.)

Searching for Text

To search for the next occurrence of text in the file, use either the slash (/) or the question mark (?) character. Follow the slash or question mark with a pattern (string of text) to search forward or backward, respectively, for that pattern. Within the search, you can also use metacharacters. Here are some examples:

• /hello-Searches forward for the word hello.
• ?goodbye-Searches backward for the word goodbye.
• /The.*foot-Searches forward for a line that has the word The in it and also, after that at some point, the word foot.
• ?[pP]rint-Searches backward for either print or Print. Remember that case matters in Linux, so make use of brackets to search for words that could have different capitalization.

The vi editor was originally based on the ex editor, which didn’t let you work in full-screen mode. However, it did enable you to run commands that let you find and change text on one or more lines at a time. When you type a colon and the cursor goes to the bottom of the screen, you are essentially in ex mode. Here is an example of some of those ex commands for searching for and changing text. (I chose the words Local and Remote to search for, but you can use any appropriate words.)

• :g/Local-Searches for the word Local and prints every occurrence of that line from the file. (If there is more than a screenful, the output is piped to the more command.)
• :s/Local/Remote-Substitutes Remote for the word Local on the current line.
• :g/Local/s//Remote-Substitutes the first occurrence of the word Local on every line of the file with the word Remote.
• :g/Local/s//Remote/g-Substitutes every occurrence of the word Local with the word Remote in the entire file.
• :g/Local/s//Remote/gp-Substitutes every occurrence of the word Local with the word Remote in the entire file, and then prints each line so that you can see the changes (piping it through more if output fills more than one page).

Using Numbers with Commands

You can precede most vi commands with numbers to have the command repeated that number of times. This is a handy way to deal with several lines, words, or characters at a time. Here are some examples:

• 3dw-Deletes the next three words.
• 5cl-Changes the next five letters (that is, removes the letters and enters input mode).
• 12j-Moves down 12 lines.

Putting a number in front of most commands just repeats those commands. At this point, you should be fairly proficient at using the vi command. Once you get used to using vi, you will probably find other text editors less efficient to use.

vi editor switches options descriptions

Hi All,
Now we are going to use world's most powerful editor vi.
Before we go further just learn how to create a hidden file in linux and see it.

$cat > [.name of file] 

A single dot in front of the file will make it hidden. For example to make a file named secret to hidden use this command

$cat > .secret
This is a secret file 

Now normal ls command will not list this file. Do a ls form current directory

$ls 

As you can see in output .secret file is not shown here. But can see hidden file with –a switch.

$ls –a
.secret 

Now rename and make it unhidden. Use mv command to rename the file

$mv .secret  test
$ls
test 

If we want to change the matter of file cat will not do it for us. So we will use vi editor to change matter of file.

$vi test 

This will open a window with bilking cursor. vi editor work in three different mode.

Esc         Command mode [press Esc key before giving any command]
Insert      Insert  mode [ to start editing use press Insert key ]
Exit        Exit mode [ Exit mode can be access via press Ecs key and :]

Beside it there are various command which can be used to control the behavior of vi editor, some of them most command are there to remember

Esc +:+w+q                    save and exit form file
Esc+:+q+!                     exit without saving
Esc+:+set nu                  to show hidden line
Esc+:+/test                   to find test word in forward directions
Esc+:+21                      to move cursor in line number 21
Esc+:+2+yy                    to copy 2 line form cursor
Esc+:+p                       to paste the copied line below the crusor
Esc+:+dd                      to remove the entire line
Esc+:+4+dd                    to remove 4 line below of cursor
Esc+:+x                       to remove single character
Esc+:+e                       to go to end of the word
Esc+:+h                       to go one character back 

Files search

Hi All,
There are two basic commands used for file searches: find and locate

find

The find command searches through directories and subdirectories for a desired file. For example, if you wanted to find the directory with the grub.conf linux boot loader file, you could use the following command, which would start the search in the top-level root (/) directory:

# find / -name grub.conf

But this search took several minutes to get it task done. Alternatively, if you know that this file is located in the /etc subdirectory tree, or /boot/grub/grub.conf you could start in that directory with the following command:

# find /etc -name grub.conf

locate

If this is all too time-consuming, RHEL 5 includes a default database of all files and directories. Searches with the locate command are almost instantaneous. And locate searches don't require the full file name. The drawback is that the locate command database is normally updated only once each day, as documented in the /etc/cron.daily/mlocate.cron script.

Getting into the Files

Now that you see how to find and get around different files, it's time to start reading, copying, and moving the files around. Most Linux configuration files are text files. Linux editors are text editors. Linux commands are designed to read text files. If in doubt, you can check the file types in the current directory with the
file * command.

cat

The most basic command for reading files is cat. The cat filename command scrolls the text within the filename file. It also works with multiple file names; it concatenates the file names that you might list as one continuous output to your screen. You can redirect the output to the file name of your choice.

more and less

Larger files demand a command that can help you scroll through the file text at your leisure. Linux has two of these commands:
more and less.
With the more filename command, you can scroll through the text of a file, from start to finish, one screen at a time. With the less filename command, you can scroll in both directions through the same text with the PAGE UP and PAGE DOWN keys. Both commands support vi-style searches.

head and tail

The head and tail commands are separate commands that work in essentially the same way. By default, the head filename command looks at the first 10 lines of a file; the tail filename command looks at the last 10 lines of a file. You can specify the number of lines shown with the -nx switch. Just remember to avoid the space when specifying the number of lines; for example, the

# tail -n15 /etc/passwd

command lists the last 15 lines of the /etc/passwd file.

cp

The cp (copy) command allows you to take the contents of one file and place a copy with the same or different name in the directory of your choice. For example, the cp file1 file2 command takes the contents of file1 and saves the contents in file2. One of the dangers of cp is that it can easily overwrite files in different directories, without prompting you to make sure that's what you really wanted to do.

mv

While you can't rename a file in Linux, you can move it. The mv command essentially puts a different label on a file. For example, the mv file1 file2 command changes the name of file1 to file2. Unless you're moving the file to a different partition, everything about the file, including the inode number, remains the same.

ln

You can create a linked file.
linked files are common with device files such as /dev/dvdwriter and /dev/par0. They're also useful for making sure that multiple users have a copy of the same file in their directories. Hard links include a copy of the file. As long as the hard link is made within the same partition, the inode numbers are identical. You could delete a hard-linked file in one directory, and it would still exist in the other directory. For example, the following command creates a hard link from the actual Samba configuration file to smb.conf in the local directory:

# ln smb.conf /etc/samba/smb.conf

On the other hand, a soft link serves as a redirect; when you open up a file created with a soft link, you're directed to the original file. If you delete the original file, the file is lost. While the soft link is still there, it has nowhere to go. The following command is an example of how you can create a soft link:

# ln -s smb.conf /etc/samba/smb.conf

sort

You can sort the contents of a file in a number of ways. By default, the sort command sorts the contents in alphabetical order depending on the first letter in each line. For example, the sort /etc/passwd command would sort all users (including those associated with specific services and such) by username.

grep and egrep

The grep command uses a search term to look through a file. It returns the full line that contains the search term. For example, grep 'vickey' /etc/passwd looks for my name in the /etc/passwd file.
The egrep command is more forgiving; it allows you to use some unusual characters in your search, including +, ?, |, (, and). While it's possible to set up grep to search for these characters with the help of the backslash, the command can be awkward to use.

wc

The wc command, short for word count, can return the number of lines, words, and characters in a file. The wc options are straightforward: for example, wc -w filename returns the number of words in that file.

sed

The sed command, short for stream editor, allows you to search for and change specified words or even text streams in a file. For example, the following command changes the first instance of the word Windows to the word Linux in each line of the file data, and writes the result to the file newdata:

# sed 's/Windows/Linux/' data > newdata

However, this may not be enough. If a line contains more than one instance of Windows, the above sed command does not change the second instance of that word. But you can make it change every appearance of Windows by adding a "global" suffix:

# sed 's/Windows/Linux/g' data > newdata

awk

The awk command, named for its developers (Aho, Weinberger, and Kernighan), is more of a database manipulation utility. It can identify lines with a keyword and read out the text from a specified column in that line. Again, using the /etc/passwd file, for example, the following command will read out the username of every user with a vickey in the comment column:

# awk '/vickey/ {print $1}' /etc/passwd

ps

It's important to know what's running on your Linux computer. The ps command has a number of critical switches. When trying to diagnose a problem, it's common to get the fullest possible list of running processes, and then look for a specific program. For example, if the Firefox Web browser were to suddenly crash, you'd want to kill any associated processes. The ps aux | grep firefox command could then help you identify the process(es) that you need to kill.

who and w

If you want to know what users are currently logged into your system, use the who command or the w command. This can help you identify the usernames of those who are logged in, their terminal connections, their times of login, and the processes that they are running.

Wildcards

Sometimes you may not know the exact name of the file or the exact search term. This is when a wildcard is handy. The basic wildcards are shown

Wildcard	Description
*	Any number of alphanumeric characters (or no characters at all). For example, the ls ab* command would return the following file names, assuming they exist in the current directory: ab, abc, abcd.
?	One single alphanumeric character. For example, the ls ab? command would return the following file names, assuming they exist in the current directory: abc, abd, abe
[ ]	A range of options. For example, the ls ab[123] command would return the following file names, assuming they exist in the current directory: ab1, ab2, ab3. Alternatively, the ls ab[X-Z] command would return the following file names, assuming they exist in the current directory: abX, abY, abZ.

env

This command displays the environment variables for the currently logged-in user.

echo

This command is used to echo a line of text on the screen. It’s frequently used to display environment variables. For example, if you wanted to see the current value of the PATH variable, you could enter
echo $PATH

top

This command is a very useful command that displays a list of all applications and processes currently running on the system. You can sort them by CPU usage, memory usage, process ID number, and which user owns them

which

This command is used to display the full path to a shell command or utility. For example, if you wanted to know the full path to the ls command, you would enter
which ls

whoami

This command displays the username of the currently logged-in user.

netstat

This command displays the status of the network, including current connections, routing tables, etc

route

This command is used to view or manipulate the system’s routing table.

ifconfig

This command is used to manage network boards installed in the system. It can be used to display or modify your network board configuration parameters. This command can only be run by the root user.

RHCE Linux system administration

Hi  All,
  Are you preparing for rhce certification ? now you can get materials and guidence here .
below given some system admin command with descriptions.

 halt
This command shuts down the operating system, but can only be run by the root user.

#halt

reboot
This command shuts down and restarts the operating system. It also can only be run by root.

#reboot           [will perform simple reboot]
#reboot -f        [will perform fast reboot ]

init 0
This command also shuts down the operating system, and can only be run by your root user.

#init 0

init 6 This command also shuts down and restarts the operating system. It also can only be run by root

#init 6

man
This command opens the manual page for the command or utility specified. The man utility is a very useful tool. If you are unsure how to use any command, use man to access its manual page. For example, you could enter man ls at the shell prompt to learn how to use the ls utility.

#man ls

info
The info utility also displays a help page for the indicated command or utility. The information displayed with info command will be in-depth than that displayed in the man page for the same command.

info ls

su
This command switches the current user to a new user account. For example, if you’re logged in as vickey and need to change to user account to vinita, you can enter su vinita at the shell prompt. This command is most frequently used to switch to the superuser root account.
In fact, if you don’t supply a username, this utility assumes that you want to change to the root account. If you enter su -, then you will switch to the root user account and have all of root’s environment variables applied.
This command require password of the user you want switch.

XerXeS DoS - Wikileaks Hacking Tool

Hi All,
Want to have a look at the tools which Jester (the one who did a Ddos distributed denial of service) attack against Wikileaks ?
just go :part-1
                        xerxes in action The tool used to Ddos Wikileak

Xerxes DOS Attack from Infosec Island on Vimeo.

This is demonstration of a XerXes DoS Attack in action against atahadi.com

Whats new from the first demo video is that more is revealed about the attack technique.

See for yourself : part-2

This second video of XerXeS shows more of the XerXeS dashboard, and reveals even more about the attack technique – It's an Enhanced version of XerXes able to dos secured Apache servers !

Take a look at 02.25 when he sets up the target server:

XerXes can now affect multiple server flavors – some still more are under development. 

This time he dropped a Secured server which is supposed have the Apache setup that is impervious to a XerXeS hit.  

Denial of Service (DoS) Attacks

The basic premise to this attack is that by sending (but never fully completing) numerous requests to Apache, one could get the Apache process to consume all system resources and stop serving up the actual web content.  

Exploitation

The Apache vulnerability is only the beginning, Xerxes will be able to hit IIS in the future. 

DoS or DDoS ? 

The attack is performed on a single low-spec computer, and while The Jester sends relatively few packets from his own machine, the attack results in brief outages of the target site. 

So he is not using any intermediaries or botnets, sorry for having wrote DDoS in my first post xD

You surely can follow Jester here:

http://twitter.com/th3j35t3r

It's working only in windows servers in IIS only  , Now the tool under development for apache in linux .