Background running of Julia on ubuntu

General Usage
1

Dear Julia users,

I am on a ubuntu machine. I want to run my Julia codes “main.jl” in background. What commend to realize this? Something like “nohup Julia command main.jl &”?

Thanks a lot!

2

That is how I do it.

3

I got this error as below

nohup: ignoring input and appending output to ‘nohup.out’
nohup: failed to run command ‘Julia’: No such file or directory

[1]+ Exit 127 nohup Julia CMD main_script.jl

4

julia is lowercase, at least on my system.

5

I tried both upper case Julia and lower case julia. Same error message.

6

“Julia main_script.jl &” is fine. But the error message shows up after adding “nohup”

7 
pkrysl@Hogwarts:~$ cat wher.jl
println("Here: $(pwd())")
exit()
pkrysl@Hogwarts:~$ nohup julia-3e47047021/bin/julia wher.jl &
[1] 14324
pkrysl@Hogwarts:~$ nohup: ignoring input and appending output to 'nohup.out'
cat nohup.out
Here: /home/pkrysl
[1]+  Done                    nohup julia-3e47047021/bin/julia wher.jl
pkrysl@Hogwarts:~$
8

The only difference I see is “julia-3e47047021/bin/julia” versus “julia”. So what is this piece of information “-3e47047021?” Thanks a lot.

9

I meant I don’t know how to specify this part “julia-3e47047021/bin/julia” for my ubuntu machine.

10

Please do which julia. That will tell you where it is.

1 Like
11

About the name of the folder: I just never bothered to rename the nightly Julia folder. It is called julia-3e47047021.

12

Ok. Thank you, Petr! With Julia’s full path, it works. I have also created an alias for the Julia path. So “nohup julia .jl &” also works now. :slight_smile:

13

I would install ‘screen’ then start a screen session in a terminal.

screen -S background-julia
julia wher.jl
Ctrl-a then D will detach the terminal and leave the process running in the bacground
screen -r in a different terminal or the same terminal will reconnect you

When working on a remote server screen is invaluable

2 Likes
14

I would also recommend tmux in place of nohup/screen.

https://github.com/tmux/tmux/wiki

1 Like
15

What is the advantage of screen comparing to nohup?

16

I heard tmux is comparable to screen. Any particular reason on recommending tmux in place of nohup/screen?

17

Just tried screen - nice tool! Thanks a lot.

I have two question which are not included in the tutorial you recommended - appreciate your help in advance.

  1. I think I accidentally opened multiple screens now; see below. How to kill the ones I don’t need.

screen -r

There are several suitable screens on:

10353.background-julia (05/07/2020 06:29:12 PM) (Attached)

10243.background-julia (05/07/2020 06:21:49 PM) (Detached)

10143.background-julia (05/07/2020 05:52:12 PM) (Attached)

10073.session_name (05/07/2020 05:36:10 PM) (Attached)

10061.session_name (05/07/2020 05:36:05 PM) (Attached)

10046.pts-1.ip-10-0-8-77 (05/07/2020 05:34:05 PM) (Detached)

  1. What are the differences between these Attached and Detached? I can only see my ubuntu in my terminal. I can open any screen with screen -r + id
18

If it’s just a single process you want to run dtach also works great