This article mainly explains Linux Process control commands , These commands are very common in work , The blogger will give specific examples and screenshots to explain
Pre knowledge ：
1. Program and process concept ：
program ： Is a file that contains executable code , Stored on disk and other media , It belongs to static concept
process ： When a program is loaded into memory by the operating system and allocated certain resources to it , This can be called a process , It belongs to dynamic concept
The following is the process state transition diagram ：
View process ：
1. ps
English original meaning ：report a snapshot of the current processes.（ Reports a snapshot of the current process ）
Function description ：ps The command is used to display the instantaneous process information of the system , It can be displayed in user input ps System process and process related information during command
grammar ：ps [options]
Common parameters ：
-l： Long format output
-u： Displays processes in the order of user name and start time
-j： Display processes in task format
-f： Displays processes in a full list format
-a： Show all user processes （ Include other users ）
-x： Show processes without control terminals
-r： Show running processes
example ：
Usually we often use ps -aux To view the system and the processes of each user ：
But what if we want to further filter the processes listed above , such as ： I just want to see users as mr.s What about the whole process ?( Most commonly used in work )
ps -aux | grep mr.s
2. top
English original meaning ：display Linux processes（ display linux process ）
Function description ： Tools for dynamically monitoring system tasks , The output results are continuous （ similar Windows Task manager for ）
grammar ：top [options]
Common parameters ：
-b： Run in batch mode , But cannot receive command line input
-c： Show command line , Not just the command name
-d N： Displays the interval between two refreshes , such as -d 5, Indicates that the interval between two refreshes is 5 second
-i： Disable the display of idle or zombie processes
-n NUM： Displays the number of updates , Then exit . such as -n 5, express top to update 5 Data exit
-p PID： Only the specified processes are monitored PID
-q： Refresh without any delay
-s： Safe mode operation
-S： Cumulative mode , Output total per process CPU,MEM Wait time
example ：
top -d 5 （ appoint 5 Refresh every second ）
In this interface ,
Press u key , Enter the corresponding user name , You can view the running process of the user
Press k key , Enter the name of the corresponding running process PID, You can kill the process
Process control ：
1. kill
English original meaning ：terminate a process（ terminate a process ）
Function description ： This command is used to send a message to a process （ adopt PID identification ） Send a signal , It is usually associated with ps and jobs Use with command
grammar ：kill -signal pid...
signal The parameters are as follows ：
1：SIGHUP, Start the terminated process
2：SIGINT, Equivalent to input ctrl+c, Interrupt the operation of a program
9：SIGKILL, Force interruption of a process
15：SIGTERM, End the process in the normal way
17：SIGSTOP, Equivalent to input ctrl+z, Pauses the progress of a process
example ：
kill -9 1024（ Forced killing PID by 1024 Process of ）
2. killall
English original meaning ：kill processes by name（ Kill process by process name ）
Function description ： The instruction uses the process name to kill the process , Use this instruction to kill a group of processes with the same name
It and kill Differences between ：kill Is to kill the designated PID Process of , However, you need to query the of the specified process PID, First use ps -aux | grep xxx
Found the process to kill PID, Pass again kill Command to kill , and killall The instruction combines the two processes into one
grammar ：killall [options] name...
Common parameters ：
-e,--exact： Exact matching of long names
-I, --ignore-case： Ignore case differences
-i, --interactive： Interactive kill process , Confirmation is required before killing
-l, --list： Print a list of all known signals
-q, --quiet： If no process is killed , No information is output
-r, --regexp： Use regular expressions to match the name of the process to be killed
-s, --signal： Replaces the default signal with the specified process number “SIGTERM”
-u, --user： Kill the process of the specified user
example ：killall game（ Kill process named game Process of ）
3. nice
English original meaning ：run a program with modified scheduling priority（ Run the program with the modified scheduling priority ）
Function description ：nice The command allows you to run the program by increasing or decreasing the default priority
grammar ：nice [OPTION] [COMMAND [ARG]...]
Adjustment range of priority ：-20 ~ 19, The smaller the value, the higher the priority
if nice The command does not specify an adjustment value for priority , By default, it is added to the original priority 10
Common commands ：
-n, --adjustment=N：add integer N to the niceness (default 10), Specifies the adjustment value of program running priority
example ：
nice -n -5 myprogram& （ In the background at the normal running priority -5 Priority run myprogram ）
4. renice
English original meaning ：alter priority of running processes（ Change the priority of running processes ）
Function description ： Change the priority of running processes
grammar ：renice [-n] priority <pid>
Common parameters ：
-n, --priority： Specifies the adjustment value of program running priority
example ：
renice -5 777（ Will be running PID by 777 The process priority of is changed to -5）
miscellaneous ：
1. &
Function description ： Put the process in the background to run
example ：
cp -r /user/* test &（ take /user Copy all subdirectories and files under the directory to test The working process under the directory is put into the background to run ）
2. keyboard entry
ctrl + z： process was suspended
ctrl + c： Process termination （ Commonly used ）
3. Process recovery
fg [n]： Will specify n The process resumes to the foreground and continues to run
bg [n]： Will specify n The process resumed running in the background
example ：
Enter first man ls, Then press ctrl + z Suspend the process , Then pass jobs View suspended processes , Then pass bg
1, Put the suspended process in the background to continue running , Finally passed fg 1, Put the background process into the foreground to run
4. jobs
Function description ： View suspended processes
grammar ：jobs
example ：jobs
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