Why to add process to background? How to do it, while executing script and when it is already running? Just a few quick examples.

Why to add process to background?

Because of two reasons:

1. thanks to that we don’t need to open new console, log in again, etc
2. thanks to that we protect ourself against the ‘Connection reset by peer’ – if some scripts are slow or long-running

Lets have a look at the some examples of background processes

First of all…

we will put our script to the background, while starting it:

./run_our_script.sh &

and check it:

ps -aux

our script should be there.
Easy, isn’t it?

now…
we will put our script to the background, while it is already running in ‘normal mode’:

Press ctrl+z to stop the current job (Yes, you can stop it! Don’t worry.).

and…

jobs

The above command will display the jobs in the shell. Something like:

[1]   Stopped                 one_app
[2]-  Stopped                 two_app
[3]+  Stopped                three_app

Ok, now we want to run ‘two_app’. In such way we can start running the specific background process. So…

bg 2

and check it…

jobs

The above command will display something like:

[1]   Stopped                 one_app
[2]   Running                 two_app
[3]+  Stopped                three_app

That means that everything is ok.
You can check it by “ps -aux”, as well.

Now… if we want to take out our script from the background

jobs

the result:

[1]   Stopped                 one_app
[2]   Running                 two_app
[3]+  Stopped                three_app

So, we just need to put:

fg 2

And everything should be fine. Our script is not in the background any more.

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Hello, I'm Karol Zielinski, internet evangelist, an entrepreneur, project manager and a web developer from Gdynia, Poland. I like creative design, good advertisement, social media and all kind of stuff around the web.

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