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How to run Linux commands in the background?

preface

Normally, when running a command on a Linux terminal, we have to wait for the previous command to be executed before entering and executing the next command, called running in the foreground or foreground process. While running in the foreground, the process will occupy your shell and you can also use the input device to interact with its terminal.

What happens when a command takes a long time to complete and you want to run other commands at the same time?

  • First: start a new Shell session and run commands in it.
  • Second: running commands in the background.

Background processes are started from the terminal and run in the background. Users do not need to interact with the terminal.

Key combination and command

For example, the httpD-2.2.17.tar. gz package will be decompressed for a long time under the terminal screen, or even a long screen brush to decompress the package, so we can press Ctrl+Z to pause and hide in the background, which will return a stop number. The process is suspended and will not continue to run.

Enter the bg command to continue executing the task in the background.

Enter the fg + serial number command to return the process to the foreground for execution.

During the execution, you can run the jobs command to view all background tasks.

# tar -zxf httpd-2.2.17.tar.gz ## Press Ctrl+Z to stop [1]+ Stopped tar -zxf httpd-2.2.17.tar.gz # bg ## Enter the bg command to continue running in the background [1]+ tar -zxf httpd-2.2.17.tar.gz & # jobs ## to view all background tasks [1]+ Done tar -zxf httpd-2.2.17.tar.gzCopy the code

Second, &

Add & after the command to make it run in the background of the terminal.

# ./yum_install.sh &
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After the command is executed, the yum script is run in the background, but the output is displayed on the terminal, so we can redirect the output of the command to the file.

# ./yum_install.sh >> 202001141411out.txt 2>&1 &
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# yum # yum # yum # yum # yum # yum # yum # yum # yum

If the script file has been executed for a period of time and is stuck, you can use the first method: jobs command

# jobs -l
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Or use the ps command

# ps -aux | grep yum_install.sh
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Third, nohup

& : You can make commands run in the background and the process will be killed when the console is shut down. If you want the process to run after the console is shut down, you need to use nohup.

No hup, no hang up.

Use nohup at the beginning of the command execution. When the console is closed, the process continues to run in the background.

# nohup ./yum_install.sh &
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As above nohup implementation methods, when the judge whether the script is done, can execute the command ps – aux | grep yum_install. Sh view;

In addition, we can output the results of the run to the nohup.log file. If no output redirection is specified, the log file is output to the nohup.out file by default.

# nohup ./yum_install.sh > nohup.log 2>&1 &
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Recommended reading

  • How to quickly recall a Forgotten Linux command?

  • With this technique, you can play with your boss even when he or she is staring at you!

  • How to efficiently manage the Network using the Linux command line?

  • SAO | how to elegant under Linux terminal operation on video?

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