There are three ways to keep the script background running in Linux: use & only put the script in the background of the current terminal, but it will terminate when the terminal is closed; combine nohup and & to make the script continue to run after the terminal is closed, and output to the nohup.out file by default; use screen or tmux to provide more flexible background management, allowing viewing and interaction at any time. In addition, you can use ps or pgrep to check existing processes, and pay attention to different methods applicable scenarios and output processing methods.

Sometimes when you run a script, you don't want it to be interrupted by terminal shutdown, or you want it to run in the background. In Linux, it is actually not difficult to implement this, only a few common methods are needed to solve it.

Use & put scripts in the background

The easiest way is to add a & when executing the command, so that it will run in the background. for example:

 ./your_script.sh &

The problem with this is that if you close the terminal window, the script will still terminate. Because although it ran away in the background, it still relies on the current shell session. If you want it to continue running, you need to combine other methods, such as what you will talk about below.

Use nohup to make the script continue to run after the terminal is closed

If you want to continue running even if the terminal script is turned off, you can use the nohup (no hang up) command. Its function is to ignore the hangup signal so that the process does not end because of the terminal closing.

It is also very simple to use:

 nohup ./your_script.sh &

After execution, a file called nohup.out will be generated by default to save the output content of the script. If you want to redirect the output to somewhere else, you can add the parameters like > output.log 2>&1 .

This method is suitable for tasks that run at one time, such as deployment scripts, data processing, etc.

Use screen or tmux to achieve more flexible background management

If you need to run scripts for a long time and may also want to come back and see the output, or even disconnect and connect back halfway, you should use screen or more modern tmux .

Taking tmux as an example, you can do this:

• Start a new session:

   tmux new -s mysession

• Run your script in this session:

   ./your_script.sh

• Press Ctrl B and then press D to get out of the current session and the script will continue to run.

• If you want to see the progress in the future, just enter:

   tmux attach -t mysession

This method is more suitable for tasks that require long-term operation or interactive viewing, such as service monitoring, development and debugging, etc.

Tips: Don't forget to check the background process

Sometimes you may forget whether you have run a script in the background. At this time, you can use ps or pgrep to find:

 ps aux | grep your_script.sh
# or pgrep -f your_script.sh

If you find that one is already running, you can decide whether to stop or continue to observe based on the PID.

In addition, if you plan to make the script run automatically, you can also add it to the @reboot task in crontab .

Basically these methods. Different scenarios choose different ways. The part that is not complicated but easily overlooks details is to figure out whether the script is really running "persistently" and how to deal with the output.

The above is the detailed content of how to run a script in the background linux. For more information, please follow other related articles on the PHP Chinese website!