Linux switch commands

1. Because many programs are resident in the memory during the operation of Linux, the disk usage efficiency of Linux is high, the asynchronous Disk/memory data transmission mode is used. Therefore, the Linux system is afraid of abnormal shutdown!

2 Linux is a multi-tasking and multi-user system

Open the terminal:
JMZ @ JMZ-desktop :~ $
JMZ: Current User Name
Followed by the computer name
After it is enabled, it is in the home directory of the current user by default ,~ /Home/JMZ
$ Is the prompt symbol of a common user.

If it is a root user, the prompt symbol is #. The root home directory is/root, which is also used ~ .

Use root with caution. Generally, the root identity is used only when the system is modified. A System Administrator usually has a common account to access computer resources.

3 shell command:

Command Option parameter 1 parameter 2 .....
Case Sensitive

1) Date time
2) Cal date
3) BC Calculator

4) Man and info are used to view the details of a command.

4 shut down, log out, and restart

Name: Shutdown
　　
Permission: System Administrator
　　
Usage: shutdown [-T seconds] [-rkhncff] time [Message]
　　
Note: shutdown can be used to shut down the program and send a message to all users before shutdown. Shutdown can also be used to restart the system.
　　
Parameters:
　　
-T seconds: Set to shut down the program in seconds.
-K: it does not actually shut down, but only sends the warning message to all users.
-R: reboot after Shutdown
-H: Shut down after Shutdown
-N
-C: cancels the shutdown action that is currently in progress.
-F: do not perform fcsk operations when shutting down (check the Linux File System)
-F: Forces The fsck action when the instance is shut down.
Time: Set the shutdown time
Message: warning message sent to all users

Name: Halt
Permission: System Administrator
Usage: Halt [-N] [-W] [-D] [-F] [-I] [-p]
Note: If the runlevel of the system is 0 or 6, the system is shut down. Otherwise, the shutdown command (with the-h Parameter added) is used to replace the system.
Parameters:
-N: Do not write the memory data back to the hard disk before shutdown.
-W: it does not actually shut down, but only writes the records to the/var/log/wtmp file.
-D: Do not write the record to the/var/log/wtmp file (-N contains-d)-f: Force shutdown. Do not call the shutdown command.
-I: Stop all network-related devices before shutdown.
-P: When the instance is shut down, the power off operation will be performed by the way.
Example:
Turn off the power after halt-P shuts down the system.
Halt-D shut down the system, but no record is left.

Name: reboot
Permission: System Administrator
Usage: reboot [-N] [-W] [-D] [-F] [-I]
Note: If the runlevel of the system is 0 or 6, restart the system. Otherwise, replace the shutdown command with the-R parameter.
Parameters:
-N: Do not write the memory data back to the hard disk before restarting.
-W: The record is not written to the/var/log/wtmp file.
-D: Do not write the record to the/var/log/wtmp file (-N contains-d)-f: Force reboot, do not call the shutdown command
-I: Stop all network-related devices before restarting.
Example:
Reboot restarts.
Reboot-W is used as a reboot simulation (only record does not actually reboot ).

Linux common command set: http://linux.chinaitlab.com/special/linuxcom/