How can I run bash script in the background?

Question

I'm learning bash scripting and I just made a short-project to notify me (with notify-send) when my battery is low or charged.

I'd like some suggestions of how can I run this script without showing the terminal. My idea is to add it in "Startup Applications" software to run when I boot the system, but I don't want to show the terminal, just to run in the background.

Answer 1

You could setup a systemd service.

You could create a file (as sudo) with you favorite editor (nano, vim etc) like:

sudo nano /etc/systemd/system/myexecuteable.service

It should contain at least the following:

[Unit]
Description=start my executable after multi-user target

[Service]
Type=simple
ExecStart=/path/to/my/executable

[Install]
WantedBy=multi-user.target

To ensure that the service will start after reboot execute: sudo systemctl enable myexecutable.service

That service will run continously if you bash has some kind of loop. If that executable has some output (use "logger for that in a bash file) you can check it any time using journalctl -u myexecutable.service

Answer 2

A script may be run in the background from the command line like this:

$ ./myscript.sh &

In other words, append & to the command.

You've said you want to run this script "without showing the termial". I think there are two ways to do this:

1. create a systemd service - as in this answer

2. start the script as a cron job when the system boots:

To set up a cron job, you will need to create a new crontab entry.

To do this, open a terminal, and type the following command:

$ crontab -e

This will open your crontab in an editor (nano is a good choice for editor). When you are in the editor, add the following line to the bottom of the file:

@reboot /home/user/myscript.sh & >> /home/user/myscript.log 2>&1 

Where /home/user/myscript.sh is the full path to your script file. Any output from your script will be redirected to the file at /home/user/myscript.log. Be sure to check this logfile for any error messages.

Save the file ( ^ o ) if using nano, and exit the editor ( ^ x).

Some things to remember:

1. Make sure myscript.sh is executable.

2. If you use any commands in myscript.sh, make sure the system knows where to find them - i.e. use a full path to the command, or declare a PATH in your script.

Let us know if you have further questions (post a comment) & we'll try to help.