Linux nohup to run programs in the background and view them (nohup and &)
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1. Background execution Generally, programs on Linux are run by executing .sh files (./sh files). What if it does not affect the operation of the current CMD window and needs to be run in the background? At this time, you need to use the nohup and & commands to achieve this. nohup java -server -Xms128M -Xmx512M -XX:MetaspaceSize=128M -jar test.jar $1 $2 $3 & (1) nohup Add to the front of a command to indicate that the command will be run without interruption. (2) & Load the end of a command, indicating that this command is executed in the background 2. View the commands running in the background There are two commands to view it, ps and jobs. The difference is that jobs can only view the tasks executed in the background of the current terminal, and it will not be visible if you change the terminal. The ps command is suitable for viewing the dynamics of instantaneous processes and can see the tasks of other terminals. (1) jobs [root@localhost test]# jobs [1]- Running nohup java -Dfile.encoding=UTF-8 -Dname=Runtime-Name -server -Xms128M -Xmx512M -XX:MetaspaceSize=128M -XX:MaxMetaspaceSize=256M -XX:+HeapDumpOnOutOfMemoryError -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -jar test.jar $1 $2 $3 & (working directory: /home/ams/ams-server/test) [2]+ Running nohup java -Dfile.encoding=UTF-8 -Dname=Container-Name -server -Xms128M -Xmx512M -XX:MetaspaceSize=128M -XX:MaxMetaspaceSize=256M -XX:+HeapDumpOnOutOfMemoryError -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -jar test1.jar $1 $2 $3 & Two background processes were started one after another, and they were both displayed after using jobs. “+” represents the most recent task (current task), and “-” represents the previous task. The jobs command can only display it when nohup and & are used in the current command line. If you write them into a .sh script and then execute the script, they will not be displayed. For example, after executing the following script, jobs are not displayed: #!/bin/bash nohup java -Dfile.encoding=UTF-8 -Dname=Runtime-Name -server -Xms128M -Xmx512M -XX:MetaspaceSize=128M -XX:MaxMetaspaceSize=256M -XX:+HeapDumpOnOutOfMemoryError -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -jar test.jar $1 $2 $3 & (2) ps command [root@localhost test]# ps -aux|grep java root 21219 0.3 3.9 6258172 148900 pts/0 Sl 10:08 0:02 java -Dfile.encoding=UTF-8 -Dname=Runtime-Name -server -Xms128M -Xmx512M -XX:MetaspaceSize=128M -XX:MaxMetaspaceSize=256M -XX:+HeapDumpOnOutOfMemoryError -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -jar test.jar root 21662 0.2 3.0 5041008 116648 pts/0 Sl 10:10 0:01 java -Dfile.encoding=UTF-8 -Dname=Container-Name -server -Xms128M -Xmx512M -XX:MetaspaceSize=128M -XX:MaxMetaspaceSize=256M -XX:+HeapDumpOnOutOfMemoryError -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -jar test1.jar root 23761 0.0 0.0 112664 972 pts/0 S+ 10:19 0:00 grep --color=auto java This is a commonly used command for viewing processes, so I won’t say more. a: Display all programs u: Display in user-based format x: Display all programs, regardless of terminal 3. Close the current background running program kill command (1) Check jobnum through the jobs command, and then execute kill %jobnum (2) Use the ps command to view the process ID PID, and then execute kill %PID If it is a foreground process, just execute Ctrl+c to terminate it. 4. Switching and controlling the foreground and background processes (1) fg command Bring the command in the background to the foreground to continue running If there are multiple commands in the background, you can first use jobs to view jobnum, and then use fg %jobnum to call out the selected command. (2) Ctrl + z command Put a command being executed in the foreground into the background and put it in a paused state (3) bg command Turn a command that is paused in the background into one that continues to execute in the background If there are multiple commands in the background, you can first use jobs to view jobnum, and then use bg %jobnum to call out the selected command for continued execution. [root@localhost test]# jobs [1]- Running nohup java -Dfile.encoding=UTF-8 -Dname=Runtime-Name -server -Xms128M -Xmx512M -XX:MetaspaceSize=128M -XX:MaxMetaspaceSize=256M -XX:+HeapDumpOnOutOfMemoryError -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -jar test.jar $1 $2 $3 & (working directory: /home/test) [2]+ Running nohup java -Dfile.encoding=UTF-8 -Dname=Container-Name -server -Xms128M -Xmx512M -XX:MetaspaceSize=128M -XX:MaxMetaspaceSize=256M -XX:+HeapDumpOnOutOfMemoryError -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -jar test1.jar $1 $2 $3 & // After using fg, move task 2 to the foreground [root@localhost test]# fg 2 nohup java -Dfile.encoding=UTF-8 -Dname=Container-Name -server -Xms128M -Xmx512M -XX:MetaspaceSize=128M -XX:MaxMetaspaceSize=256M -XX:+HeapDumpOnOutOfMemoryError -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -jar test1.jar $1 $2 $3 ^Z // After pressing ctrl+Z, put Task 2 in the background and pause it [2]+ Stopped nohup java -Dfile.encoding=UTF-8 -Dname=Container-Name -server -Xms128M -Xmx512M -XX:MetaspaceSize=128M -XX:MaxMetaspaceSize=256M -XX:+HeapDumpOnOutOfMemoryError -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -jar test1.jar $1 $2 $3 // After using bg, activate the operation of task 2 [root@localhost test]# bg 2 [2]+ nohup java -Dfile.encoding=UTF-8 -Dname=Container-Name -server -Xms128M -Xmx512M -XX:MetaspaceSize=128M -XX:MaxMetaspaceSize=256M -XX:+HeapDumpOnOutOfMemoryError -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -jar test1.jar $1 $2 $3 & The above is the full content of this article. I hope it will be helpful for everyone’s study. I also hope that everyone will support 123WORDPRESS.COM. You may also be interested in:
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