NO21 llinux file types and extensions--file permissions--Hard links

file types and extensions for Linux

I. Types of documents:
1. Ordinary files (regular file) the first character is [-]
Including:
① Plain text file (ASCII): This is the most common type of file in a Linux system, known as a plain text file. is because the content is data that we humans can read directly, such as numbers, letters, and so on.
② binary (binary): Your Linux executable (scripts, text-based batch file does not count) is in this format.
③ data Format file: Some programs read files in certain formats during operation, and those files in a particular format can be referred to as data files. Cat is generally used to see all garbled.

2. Table of Contents (directory): The first character is [d]

3. Connection file (link) The first character is [l]

4. Equipment and equipment files
Fast device files, that is, some storage files, such as hard disk, floppy disk, etc., the first character is [b]
A character device file, which is an interface file for some serial ports, such as a keyboard, mouse, etc., the first character is [C]

5. Socket (sockets) The first character is [s]
Also known as data interface files, this type of file is usually used for data connections on the network. We can start a program to listen to the client's request, and the client can communicate through the data interface file.

6. Pipeline (Fifo,pipe) The first character is [P]
FIFO is also a special type of file, his main purpose is to solve the error problems caused by multiple programs accessing a file simultaneously, first-in-first-out.
Note: It is best not to modify the device files, the link file is a shortcut to win.

Ii. Linux file extension
In general, the files in Linux do not need to be extended, which is very different from windows, we know that in Windows, the executable file extension end is usually. Exe,.com,.bat, and in Linux files can be executed is to see if the permission bit x-bit x, The picture file extension end is usually. Jpg,.gif,.bmp,.png, and so on.

The role of the extension under Linux:
1 TAR,.TAR.GZ,.TGZ,.ZIP,.TAR.BZ is a compressed file, the creation command is generally tar,gzip,unzip, etc.
2 SH represents a shell script file, a program developed through the shell language.
3 PL Represents a Perl language file developed by the Perl language program.
4 py represents a Python language file, a program developed through the Python language.
5 Html,htm,php,jsp,do file that represents the language of the Web page.
6. conf represents the system configuration file.
7. RPM indicates the RPM installation package file.

Third, the file name limit of Linux
Under Linux, when using the default Ext2/ext3 file system, the filename length is limited to:
? The maximum capacity file name for a single file or directory is 255 characters;
? The full file name including the full path name and the login (/) is 4,096 characters.
Also try to avoid using special characters because they have special meanings in command line mode.

File permissions:

Link:

Hard-Link creation:

NO21 llinux file types and extensions--file permissions--Hard links