After Restart Server Instances CentOS 7 .. All websites Down and Can't login to Server .. How to solve it? This is solution

After Restart Server Instances CentOS 7 .. All websites Down and Can't login to Server .. How to solve it? This is solution

I use vultr server.. but today  that server down after I restart server in CentOS 7 .

Frustration caused server down and all website down, can't login to server. Don't worry, this is solution..

1. contact to vultr using ticket to make you can see GRUB menu.
2. Find the kernel line (it starts with "linux16"), change ro to rw init=/sysroot/bin/sh
3. Press CTRL+X or F10 to boot single user mode.
4. Access the system with the command: chroot /sysroot
5. Edit /etc/selinux/config and change "enforcing" to "disabled" .. use method to edit Editing files with vi  

vi /etc/selinux/config
change "enforcing" to "disabled"
press  Escape
press :wq

6. reboot -f

Your server will reboot.. wait until display need login.. congrulation.. your server up now

Editing files with vi

https://www.control-escape.com/linux/editing-vim.html

The thing you have to understand about vi and its work-alike editors is modality. Most programs have just one mode, accepting input and placing it at the cursor. This is what you probably expect from a program. But vi has other modes. When you start vi, you’ll be in “Normal” mode, which is really command mode. When you are in Normal mode, whatever you type is considered not to be input, but commands that vi will try to execute.

This may sound a little crazy, but it is actually a very powerful way to edit documents. Even if you hate it, the ubiquity of vi means that you’re going to need to learn the basics, because sometimes you just have to use it. On the other hand, if you enjoy working at a command line, then you may end uploving vi.

Lesson 1: How to Quit vi

Since vi is the default editor, there’s a good chance you got dropped into it without knowing it. This can be extremely frustrating if you don’t know your way around the program.

To exit vi without saving changes, hit Escape a couple of times to ensure you are in Normal mode, and then type:

:q!

Lesson 2: Editing with vi

Start vi and press i. The cursor may change shape, and INSERT is displayed at the bottom of the screen (in most vi clones). You are now in insert mode — all your keystrokes are entered into the current buffer and are displayed to the screen.

Hit the Escape key. The cursor changes shape again, and INSERT has disappeared. You are back in Normal mode. Hitting Escape a few times will pretty much always cancel whatever you are doing and return you to Normal mode.

Command mode is also where you move around in the file. On most systems, you can use the arrow keys to move the cursor. If that fails, cursor movement can be accomplished with the hjkl keys:

h   move left one character
j   move down one character
k   move up one character
l   move right one character

vi has its own command line, which you access by typing a colon. Commands typed at the command line will not be executed until you hit Enter, just like in the shell.

Many of the commands that you will use in command mode begin with a colon. For example, the command to quit is :q, as we learned in Lesson 1 above. Actually, in Lesson 1 we added !, which tells vi to “force” the operation. If you have edited the file, typing :q will not immediately exit the program, but instead produce this error message:

E37: No write since last change (add ! to override)

To save your changes, use the :w command (“Write”). You can save and quit all in one go by typing both commands together:

:wq

Of course, if you started vi without giving a file name, you’ll need to provide one. For example, to save your working file as test.txt, you would type:

:w test.txt

Try editing some text now.

• Start vi
• Hit i to go to Insert mode.
• Type some text.
• Hit Escape to return to Normal mode.
• Type :w test.txt to save your work
• Type :q to quit

vi Quick Reference

Movement

h, j, k, l

left, down, up, right

$

To the end of the line

^

To the beginning of the line

G

To the end of the file

:1

To the beginning of the file

:47

To line 47

Editing

dd

Remove a line

5dd

Removing five lines

r

Replace a character

x

Delete a character

5x

Delete 5 characters

u

Undo last action

J

Join current and next lines (Note the capital — hold the Shift key)

Saving and Quitting

:q

Quit

:q!

Quit without saving

:wq

Write and quit

:w

Write (without quitting)

:e!

Reload currently open file from disk

:w test.txt

Write buffer to file test.txt

:e test2.txt

Open file test2.txt