10 characters indicate the file category and permissions, as follows: the first character indicates the file category, and its meaning is as follows:-:ordinary file d: directory file b: block device file c: character device file l: nine characters after the symbolic link file indicate three groups of access permissions: 1 The three characters in the group are the permissions of the authorized file owner; The three characters in the second group are the permissions granted to users in the same group; The three characters in the third group are the permissions granted to other users. The three characters in each group respectively represent one-time read, write and execute permissions, where: r: indicates read permissions w: indicates write permissions x: indicates execute permissions-:indicates no corresponding permissions.

Special characters and shortcut keys commonly used by bash in linux?

Common shortcut keys and special symbols in Linux;

Ctrl+c termination command

Ctrl+l clears the screen.

Ctrl+d exits the current user.

Esc+。 Use the content after the last space of the previous command.

The Ggwim command opens the file and moves the cursor to the first line.

Shift+g vim command opens the file and moves the cursor to the last line.

Shift+d vim command deletes the content from the cursor position to the end of the line.

Used in files opened by the o vim command to insert a blank line next to the line where the cursor is located.

Special symbolic meaning

Single quotation marks, whose contents will not be parsed.

Double quotation marks, if the content has special symbols, will be parsed and run.

`` back quotation marks, which get the result of command running, equivalent to $ ()

& gt redirection: clear the contents of the file first, and then write the contents to the file.

& gt& gt Append redirection adds content to the last line of the file.

2> error redirection: first clear the contents of the file, and then only write the error information to the file.

2>& gt Error in appending redirection, only error report information is added to the last line of the file.

~ current user's home directory

! 1. Invert 2. Find and run the history command.

# 1. Note 2. 2. Command prompt of 2.root user

$ 1. Take out the contents of the variable. 2. Command prompt of ordinary users.

* One of the wildcards, which means any character.

* means ending with the specified character.

* means starting from the specified character.

* * indicates that it contains the specified character.

escape character

Multiple commands can be connected and executed in sequence. If there is an error in the command, an error message will be displayed and subsequent commands will not run.

|| You can connect multiple commands and execute them in turn. If there is an error in the command, an error message will be displayed. Continue to run until the first correct command, and subsequent commands will not run.

{} braces, one of the wildcards, can execute commands in batches.

For example: echo{ 1? 5} Output: 12345

For example: echo{a? C} output: abc

For example: echo20{0 1? 5} Output: 200 12002200320042005

Which character in linux stands for symbol chain class?

The character l in Linux stands for symbolic link. L stands for link link.

What is the purpose of linux to create soft connections? How does a cd get into a soft connection?

The method of creating symbolic link is: ln-s source file/directory name symbolic link name, for example, ln-s/usr/bin/python3.3/usr/bin/pythonln-s/etc/apache2/sites-enablers ~/webcfg. If the source of the symbolic link is a directory, you can enter it with ordinary cd commands, such as CD ~/.