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Let's start by introducing the general role of the various directories under Ubuntu:
This is the root directory, a computer has only one root directory, all the files are started here. For example: When you enter "/home" in the terminal, you are actually telling the computer to start with the/(root directory) and then go to the home directory.
The directory of the system administrator (root user). As far as the system administrator's authority is, I'm not talking nonsense here. Therefore, be careful with the root account.
system startup files, all files related to system startup are saved here.
Here is the procedure for storing the system.
The system configuration files are mainly stored.
The main store is the files related to the device (including peripherals) (Unix and Linux systems treat the device as a file). Do you want to connect the printer? The system starts working from this directory. There are also some disk drivers, USB drivers, etc. are put in this directory.
Your personal data is primarily stored here. Each user's settings file, the user's desktop folder, and the user's data are all placed here. Each user has his or her own user directory, located at:/home/user name. Of course, the root user is excluded.
This is the temp directory. For some programs, some files are used two times a time, they are no longer used, and files like this are placed here. Therefore, do not put the important data here oh.
In this directory, you can find additional tools that are not suitable for use in/bin or/etc directories. Like games, some printing tools and so on. The/usr directory contains many subdirectories: The/usr/bin directory is used for storing programs, and/usr/share is used to store some shared data, such as music files or icons, etc./usr/lib directories are used to store those that cannot be run directly, However, it is a function library file that is necessary for many programs to run. Your package Manager will automatically help you manage the/usr directory.
There are some optional programs that are mainly stored here. Would you like to try the latest Firefox beta? Put it in the/opt directory, so that when you're done trying to erase Firefox, you can simply delete it without affecting any other settings on the system. The program installed in the/OPT directory, all of its data, library files, etc. are placed under the same directory.
The main store is the software that is installed manually, that is, software that is not installed through "new" or apt-get. It has a similar directory structure to the/usr directory. Let the package Manager manage the/usr directory and put the custom script (scripts) under the/usr/local directory.
This directory is used to mount the USB interface of the mobile hard disk (including USB stick), CD/DVD drive and so on.One, Linux under the terminal Common command
Ubuntu Terminal Common Commands
# CTRL + L-Clear screen
# CTRL + C-Abort command
# Ctrl + D-exits the shell as if it could also represent EOF
# CTRL + Z-the current process is placed in the background and FG is restored.
# Ctrl + R-Find from command history
# CTRL + A-cursor moves to the beginning of the line
# CTRL + E-the cursor moves to the end of the line
# Ctrl + U-clear the cursor to the beginning of the character
# Ctrl + W-clear the cursor before a word
# Ctrl + K-clears the character of the cursor to the end of the line
# CTRL + T-swap the first two characters of the cursor
# Ctrl + Y-paste the characters that were removed from the previous Ctrl+u class command
# CTRL + P-Previous command
# CTRL + N-Next command
# Ctrl + V-Input control word such as CTRL + V.
The VI Editor is the standard editor for all UNIX and Linux systems, introducing its usage and a small number of instructions. Because the VI editor is exactly the same for any version of UNIX and Linux systems, you can learn more about it in any other place where VI is introduced. VI is also the most basic text editor in Linux, after learning it, you will be in the world of Linux unimpeded.
Before all commands are executed, press ESC first
Basic concepts of 1 VI
Basically, vi can be divided into three states, namely command mode, insert mode (and bottom line mode), and the function of each mode is as follows:
1) command-line mode
Controls the movement of the screen cursor, the deletion of characters, words, or lines, moving and copying a section and entering insert mode, or to last line mode.
2) Insert mode
Only in the Insert mode, you can do text input, press "esc" to return to the command line mode.
3) Bottom Line mode
Save or Exit VI, or you can set the editing environment, such as looking for a string, listing line numbers ... such as
In general, however, when we use the VI to simplify the two mode, that is, the bottom row mode (last lines) is also counted in the command line mode (commands mode).
Basic operation of 2 VI
A) Enter VI
After the system prompt symbol to enter VI and file name, go to the VI Full screen editing screen:
$ VI myfile
However, it is important to note that after you enter VI, you are in command mode and you want to switch to insert mode to enter text. First Use VI people will want to use the next key to move the cursor, the result of the computer has been a beep, the gas to death, so enter the VI, do not move, switch to "insert mode" and then!
b) switch to insert mode to edit the file
Press the letter "i" under Command mode to enter "Insert Mode", and you can start typing the text again at this point.
c) Toggle of Insert
You are currently in "Insert Mode", you can only enter text, if you find the wrong word! To move back with the cursor key, delete the word, then click the "esc" key to go to "command mode" and then delete the text.
d) Exit VI and save the file
Under Command mode, click the ":" colon key to enter "last line mode", for example:
: w filename (enter "w filename" to save the article with the filename you specified)
: Wq (input "wq", save and Exit VI)
: q! (Enter q!, do not save the mandatory exit VI)
3 command-line mode function keys
1). Insert mode
Press "i" switch into insert mode "insert mode", press "I" into the insertion mode is the beginning of the cursor from the current position to enter the file;
After pressing "a" into insert mode, the text is entered from the next position at the current cursor position;
When you press "o" to enter insert mode, you insert a new line and enter text from the beginning of the beginning.
2). Switch from insert mode to command line mode
Press the "esc" key.
3). Move the cursor
VI can be directly on the keyboard with the cursor to move up and down, but the normal VI is the lowercase English letter "h", "j", "k", "l", respectively, control the cursor left, bottom, upper, and right one grid.
Press "ctrl"+"b": The screen moves one page to the back.
Press "ctrl"+"f": The screen moves one page to the front.
Press "ctrl"+"u": The screen moves the half page toward the back.
Press "ctrl"+"d": The screen moves the half page toward the front.
"0" by number: Moves to the beginning of the article.
Press "g": Move to the end of the article.
Press "$": Moves to the end of the line where the cursor is located.
Press "^": Moves to the beginning of the line where the cursor is located
Press "w": Cursor jumps to the beginning of the next word
Press "e": Cursor jumps to the end of the next word
Press "b": Cursor back to the beginning of the last word
Press #l: The cursor moves to the first # position of the line, such as: 5l,56l.
4). Delete text
"x": Each time you press the cursor, delete the "after" character at the position where the pointer is located.
#x: For example, "6x" represents the "after" 6 characters of the location where the cursor was deleted.
"x": Uppercase X, each time it is pressed, deletes the "front" character at the location of the cursor.
"#X": for example, "20x" represents the "front" 20 characters of the location where the cursor was deleted.
"dd": Delete the line where the cursor is located.
"#dd": Deletes the # line starting at the line where the cursor is located
"yw": Copies the characters from the cursor to the end of the word into the buffer.
"#yw": Copy # words to Buffer
"yy": Copy cursor line to buffer.
"#yy": for example, "6yy" represents a copy of 6 lines of text from the line where the cursor is located.
"p": Paste the characters in the buffer to the cursor location. Note: All copy commands related to "Y" must be mated with "P" to complete the copy and paste function.
"r": Replaces the character at which the cursor is located.
"r": Replaces the character where the cursor is located until the "esc" key is pressed.
7). Reply to Last action
"u": If you mistakenly execute a command, you can press "u" immediately to go back to the previous action. Multiple replies can be performed by pressing "U" multiple times.
"cw": Change the word-to-tail at the cursor location
"c#w": For example, "c3w" represents a change of 3 words
9). Jump to the specified line
"ctrl"+"g" lists the line number of the line where the cursor is located.
"#G": for example, "15g", which means moving the cursor to the beginning of the 15th line of the article.
4 last command about line mode
Before using "last line mode", remember to press "esc" to make sure you are under "command mode" and then press ":" Colon to enter "last line mode".
A) List line numbers
"set nu": After you enter "set nu", the line numbers are listed before each line in the file.
B) jump to a line in the file
The "#":"#" number represents a number, enter a number after the colon, and then press ENTER to jump to the line, such as entering the number 15, and then enter, you will jump to the 15th line of the article.
C) Find characters
"/Keyword: First press the"/"key, and then enter the character you want to look for, if the first keyword is not what you want, you can always press"n"will look back to the keyword you want.
"? keyword": Press "?" first Key, and then enter the character you want to find, if the first keyword is not what you want, you can always press "n" will look forward to the keyword you want.
D) Save the file
"w": Enter the letter "w" the colon to save the file.
E) Leave VI
"q": Press "q" is to exit, if you cannot leave VI, can be "q" followed by a "!" Forced to leave VI.
"wq": Generally recommended to leave, use with "w", so you can also save the file when exiting.
5 VI Command List
1. The following table lists the functions of some keys in the command mode:
Move left cursor one character
Move the cursor one character to the right
Move the cursor up one line
Move the cursor down one line
Cursor moves to the beginning of the line
Number "0", the cursor moves to the beginning of the article
Cursor moves to the end of the article
Move cursor to end of line
Flip the screen forward
Flip the screen backwards
Turn Half-screen forward
Turn Back half screen
Insert a character before the cursor position
The next character at the cursor position begins to increment
Insert a new row, starting at the beginning of the line
Fallback from input state to command state
Delete the character following the cursorX
# characters after the cursor is deleted
(uppercase x), delete the character in front of the cursorX
Delete the # characters before the cursor
Delete the line where the cursor is locatedDd
Remove the # line from the number of lines that the cursor contains
Copy a word where the cursor is locatedyw
Copy the # Word where the cursor is located
Copy a row where the cursor is locatedYy
Copy the # line from the number of lines where the cursor is located
Change a word in the position of your cursorcw
Change the # Word where the cursor is located
2, the following table lists some instructions in the line command mode
Save the file you are editing as filename
Save the file being edited as filename and exit VI
Discard all changes, exit VI
Show line Numbers
Find, enter what you are looking for in/after
with/or, if the search is not the keyword you are looking for, press N or backwards (with/to) or forward (with?) to continue looking until you find it.
For the first use VI, there are a few notes to remind:
1. When you open a file with VI, you are in command mode, and you want to switch to insert mode to enter text. Toggle method: Click on the letter "i" "Command mode" to enter "Insert Mode", then you can start to enter the text.
2, after editing, you need to switch from insert mode to command line mode in order to save the file, switch method: Press the "esc" key.
3. Save and exit the file: Enter in command mode: WQ! (Don't forget to wq the front:)
[Turn]linux under the terminal common commands and the VI command to modify the file and save the use method
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