Linux Learning-----3

Advanced Directives

1.hostname instruction function: Operation server hostname (read settings)

Hostname output the full host name

Hostname-f to output the fully qualified domain name of the current host

2.id instruction function: View some basic information of a user (including User ID user group ID additional group ID ...) ）

This directive displays the current user by default if you do not specify

Syntax: ID defaults to display information that executes the current user

Syntax: ID user name displays basic information for the specified user

Verifying User Information cat/etc/passwd

Verifying user group Information Cat/etc/group

3.whoami Command function Displays the currently logged in user name

Typically used by shell scripts to get the current log operator who is

4.PS-EF directive (emphasis)

Instruction PS to view process information for the current server

Option:-e indicates that all processes are listed

-F Show All columns

UID the user ID that the process executes

PID Process ID

PPID the process's parent process if no parent process is found the process of the program is called a zombie process

C CPU occupancy rate is in the form of percent

Stime start time of the process

TTY Terminal Equipment identification number of the device initiating the process if it is? Indicates that the process is not initiated by an end device

Time when the process was executed

CMD the process name or the corresponding path

Filter the status of the process you want to see in the PS results

Ps-ef | grep cmd name

5.top instruction function: View the server's process footprint resources

Syntax: Top (enter command) dynamic display

Q (Exit command)

The greater the priority of the PR priority, the higher the priority of the queue

VIRT virtual Memory Request 500M actually uses 320M virtual memory as 500M

RES resident Memory Request 500M actually uses 320M of virtual memory for 320M

SHR Shared Memory Request 500M actually uses 320M but it contains the call overhead for other processes

This part of the overhead is shared memory

Calculate the actual memory used by a process = resident memory-Shared memory

Men memory Occupancy Percentage

Convenient shortcut keys

M descending order of results by memory from high to low

P sort results in descending order of CPU usage from high to low

Number 1 When the server has multiple CPUs, use 1 to toggle whether to expand the display of individual CPU details

6.DU-SH directive function: View the real size of the directory

Option meaning:-s Displays the total size only

-H for display in a higher readability format

Syntax format: Du-sh directory path

7.find command function: Find files (55 parameters)

Syntax: Find path range option value

Option:-name Search by document name (fuzzy search is supported)

-type Search by Document Type "-" means that the file (replaced with F in search) "D" means a folder

Case use Find search httpd.conf

Find-name httpd.conf

Case Search all conf suffix files in the ETC directory

Find/etc-name *.conf

Case: Use Find to search all files in the SANE.D directory under the ETC directory

find/etc/sane.d/-type F

Case: Use Find to search all folders in the ETC directory

Find/etc-type D

8.service instruction (emphasis) function to control some software services start stop restart

Syntax: Service name Start/stop/restart

Apache (Web services software) service that needs to start the native installation is named httpd

Service httpd Start

Ps-ef | grep httpd

9.kill instruction (emphasis) Action: Indicates the kill process (when encountering a zombie program or some reason to close the program)

Syntax 1:skillall process name

Syntax 2:skill process PID

Case needs to kill Apache's process/

10. IFCONFIG directive (emphasis) function: For operating network card related instructions

Syntax: ifconfig

11.reboot instruction function: Restart the computer

Syntax 1:reboot restart

Syntax 2:reboot-w analog reboot, but does not restart

12.shutdown directive function: Use caution with caution in shutting down the machine

Syntax: Shutdown-h now (shut down immediately) or shutdown-h 15:25 (timed off)

If you want to cancel the shutdown schedule for the previous version of centos7.0 CTRL + C

For centos7.0 later version shutdown-c

13.uptime instruction function: Output the duration of the computer (computer from boot to present)

14.uname instruction function: Get information about the computer system

Uname get the type of operating system

UNAME-A Get all system information (type all hostname kernel version release time Open source plan)

15.NETSTAT-TNLP instruction function: View network connection Status

Option Description:

-T indicates a connection that lists only the TCP protocol

-N means converting an address from a combination of letters to an IP address, converting the protocol into a port number to display

-L means filter out "state" to list connections whose value is listen (listening)

-P shows the process PID and process name initiating the connection

16.man instruction function: Manual (manual with full Linux content)

Syntax: Man instruction name

Practice:

Linux Learning-----3