&& in bash script using GNU "parallel"

Question

I would like to run my bash my_script.sh using GNU parallel:

parallel < my_script.sh

where my_script.sh is:

command1 && command2
command3 
command4

Will command1 and command2 run in parallel or sequentially.
In case I am not clear:
command1
command2
command3
command4

or

command1 -> command2
command3
command4

?

Thank you!

GNU `parallel` is a separate project, not part of bash, and it has its own tag. — Charles Duffy, Oct 22 '20 at 20:18
This may help: https://stackoverflow.com/questions/3004811/how-do-you-run-multiple-programs-in-parallel-from-a-bash-script — User123, Oct 23 '20 at 03:48
@user123 Does & runs threads in time while parallel in differents cpus? — aerijman, Oct 23 '20 at 15:30
`&` runs **processes** in the background, not threads. You shouldn't really concern yourself with which CPU the OS uses. — Mark Setchell, Oct 23 '20 at 15:34

Qmski · Accepted Answer · 2020-10-23T05:45:58.217

0

&& lets you do something based on whether the previous command completed successfully.

It will run like this:

command1 -> command2 (only if the exit status of "command1" is zero)
command3
command4

edited Oct 23 '20 at 05:45

answered Oct 22 '20 at 20:13

Qmski

if I use semicolon instead of `&&`, will it run in parallel 1+2 - 3 - 4 ? – aerijman Oct 22 '20 at 20:52
1

@aerijman Please read this article, especially section "Brute Force" should resolve your doubts (if you want to execute each command parallel). [Get more done at the Linux command line with GNU Parallel](https://opensource.com/article/18/5/gnu-parallel). If you want to execute the command sequentially (line after line) use normal run: `./my_script.sh` – Qmski Oct 23 '20 at 05:39

1 Answers1