[Linux 4] timed task scheduling and process service management, Java Architect with ten years of development experience

（1） Every other minute , Append the current date information to /tmp/mydate In file

*/1 * * * * date >> /tmp/mydate.txt

（2） Every other minute , Append the current date and calendar to /tmp/mydate In file

step ：

1. vim /home/my.sh Write content date >> /home/mydate and cal >> /home/mydate

2. to my.sh Add execution permission ,chmod u+x /home/my.sh

3. crontab -e increase  */1 * * * *  /home/my.sh

（3） Every morning 2:00 take mysql database testdb, Backup to file .

Instructions ：mysqldump -u root -p password database > /home/db.bak

1. crontab -e

2. 0 2 * * *  mysqldump -u root -proot testdb > /home/db.bak

4、at Timing task

（1）at： One time scheduled tasks

（2）at Command format

at [ Options ][ Time ]

Ctrl + D end at Command input

Two 、Linux Partition and mount

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1、 Partition command ：fdisk /dev/sdb

2、 Disk status query

Basic grammar ：df -h

3、 Disk condition utility instruction

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3、 ... and 、 The network configuration

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1、NAT The network configuration

2、 configure gateway 192.168.2

3、 Design host names and hosts mapping

Modify the file in /etc/hostname Appoint

Four 、 Process management

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1、 Process number

stay Linux in , Each executed program is called a process , Each process is assigned a ID Number （pid, Process number ）.

2、ps Instructions

Display the process executed by the system

attribute ：

-a： Display all process information of the current terminal

-u： Display process information in user's format

-x： Display the parameters of the background process

Pagination display ：ps -aux | more

Filter display ：ps -aux | grep sshd

3、ps Show detailed information

1. USER： User name

2. PID： Process number

3. %CPU： Process occupation CPU Percent of

4. VSZ： Virtual memory size occupied by the process （ Company ：KB）

5. RSS： The physical memory size occupied by the process （ Company ：KB）

6. TT： Terminal name , abbreviation

7. STAT： Process status （S- sleep ,s- Indicates that the process is the forerunner of the session ,N- Indicates that the process has a lower priority than normal ,R- Running ,D- Wait for a short time ,Z- The dead process ,T- Being tracked or stopped, etc ）

8. STARTED： Start time of the process

9. TIME：CPU Time , That is, process use CPU The total time of

10. COMMAND： Commands and parameters used to start the process , If it is too long, the display will be truncated

4、 Terminate the process

kill and killall

Basic grammar ：

kill [ Options ] Process number （ Function description ： Kill the process by process number ）

killall Process name （ Function description ： Kill process by process name , Wildcard characters are also supported , This is useful when the system is slow due to excessive load ）

Common options ：-9 Indicates that the process is forced to stop .

5、 View the process tree

pstree [ Options ], You can more intuitively view the process information

Common options ：

-p： Show progress pid

-u： Show users of the process

5、 ... and 、 Service management

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1、 brief introduction

The essence of service is process , But it's running in the background , It's usually listening on a certain port , Waiting for requests from other programs , such as mysql、sshd、 Firewall, etc , So we call it a daemon , yes Linux The most important knowledge point in .

2、service Management instructions

1. service service name [start | stop | restart | reload | status]

2. stay centos7.0 after , Many services are no longer used service, But use systemctl

3. service The service of command management is /etc/init.d see

3、chkconfig Instructions

adopt chkconfig You can set self startup for each running level of the service / close .

Basic grammar ：

• chkconfig --list [| grep xxx]

• chkconfig service name --list

• chkconfig --level 5 service name on/off

4、systemctl Instructions

Basic grammar ：

systemctl [start | stop | restart | reload | status] service name

systemctl The service of command management is /us/lib/systemd/system see

systemctl Set the self starting state of the service

1. systemctl list-unit-files [|grep service name ]（ View service startup status ,grep It can be filtered ）