Linux Operating System Basics

When you encounter some commands that you don't understand, you can look at the command as an internal/external command, and then use the Help/--help/man command to view the help.

Describes how to use some common commands:

1.cd

CD dir switches the working directory to the DIR directory to open the function of the directory file;

The CD switches the working directory to the home directory of the currently logged-in user;

CD-Switches The working directory to the working directory of the first time, and switches between the two directories;

CD ~ Switch The working directory to the home directory;

CD ~usename switches the working directory to the specified user's home directory, which is limited to the root user.

2.pwd

Print the name of the current working directory

3.ls

-a displays all files, including hidden files (in Linux, all files that begin with. are hidden);

-a displays except./. Any items other than, including hidden files;

-D does not display contents of the directory, only the directory name of the directory;

-L long format to display detailed properties of the file;

-H easy-to-read file size format, usually using 1024 bytes for conversion;

-R reverse output;

-R recursively displays the contents of the directory and subdirectories;

-Z Displays the file's SELinux security context;

4.mkdir

Create a catalog file;

-p When creating the directory, check that the parent directory exists, does not exist and creates the parent directory;

-V shows the execution of the command

5.rmdir

The command to delete directory files, but only empty directories can be deleted, and non-directory files cannot be deleted;

Options and mkdir command options extrapolate;

6.rm

Very powerful Delete command

-I interactive deletion with the user;

-F Force Delete, no interaction;

-R recursive deletion;

7.touch

Change the timestamp of the file, but you can create the file;

8.stat

View the status of a file

-C to append a format character to display the specific properties of the file in a specific format;

9.nano

Compare basic text editing commands, do not do too much explanation, mainly use Vi/vim;

10.cat

Connect files and view files, can write multiple files;

-B numbering of non-empty line contents;

-N to number all lines;

-S merge multiple lines of blank behavior row;

-e Displays the terminator at the end of each line in the document, expressed in $;

11.tac

Reverse output of cat;

12.head

The first ten lines of the file contents are displayed by default;

-N Displays the contents of the first n rows of a file, or it can be abbreviated as a digital form;

-C output by character, previous # multiple characters [b|k|m|g];

13.tail

The default display of the following 10 lines of content;

The option is similar to head;

14.more/less

pagination Display command;

But more can only be shown backwards, and less can be displayed back and forth;

Next, you'll describe some of the time-related commands:

15.hwclock (Clock)

Display Hardware clock life

-s with hardware clock as reference, set system clock;

-W with the system clock as the reference, set the hardware clock;

16.date

Commands to display the system clock

17.cal

commands to display calendars

Shutdown command:

18.halt

Not recommended to use, directly unplug the meaning of the system's current operation of the task is not to save;

19.shutdown

Option to operate the shutdown time, but also cancel the shutdown operation;

-R reboot the system, restart the meaning;

-H shut down the system;

-C cancels a shutdown operation that is about to be performed;

20.exit

End the current shell and take advantage of this command to prevent repeated opening of the same user shell, consuming too much system memory;

21.cp

Physical backup, divided into single source replication and multi-source replication, single source replication when the target can be non-existent, multi-source target can be a directory. The CP command requires at least two parameters, usually the last parameter is the target location of this replication, if a single source replication, the target can not exist, the target can be non-directory files, and can change the file name, and the multi-source replication destination must be a directory and the replication process cannot change the file name.

-D copy of the source if it is a symbolic link file, the symbolic link file is copied directly to the target location, not the linked file;

-P is able to preserve file permissions, ownership, and timestamp information when copying files;

-R/R the ability to recursively copy directories and files in a directory;

-A is equivalent to the combination option of the PDR option;

22.mv

Move the file to the target location or use it to change the filename;

-F Force overwrite files with duplicate names in the target location;

23.which

Find out if the executable file exists and where the display resides;

Example: # which VI

/usr/bin/vi

24.whereis

Locates executable files, source code files, and Help files in the file system location.

-B Locate the executable file;

-m location Help file;

-S location source code files;

-U searches the default path for files other than executables, source code files, and Help files;

-b Specifies the path to the search executable file;

-m specifies the path of the search Help file;

-s Specifies the path of the search source code file;

25.whatis

equivalent to running man-f;

Example: Whatis VI

VI (1)-VI improved, a programmer's text editor

Linux Operating System Basics