parallel bash commands with a certain delay in between

Question

I am already familiar with sleep and usleep commands. But I am not sure how to use them for parallel commands which are supposed to have a certain delay with respect to the start time of the previous command. I mean something like this (commands 1 to n are supposed to be run in parallel with a delay between their start time):

Command 1's start time: 0
Command 2's start time: 0+d
Command 3's start time: 0+2d
.
.
.
Command n's start time: 0+(n-1)d

How many tasks are there? And what sort of delay are you envisaging? — Mark Setchell
– Mark Setchell, Commented Jan 14, 2015 at 21:11

dg99 · Accepted Answer · 2015-01-14 21:15:16Z

3

If you're just running them in the background in the shell then you could simply have each loop sleep after starting its command.

for cmd in cmd1 cmd2 ... cmdN; do
    eval ${cmd} &
    sleep ${d}
done

answered Jan 14, 2015 at 21:15

dg99

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3 Comments

ShellFish Over a year ago

Maybe ad a caveat that the commands should be wrapped in quotes to handle arguments and options. Alternatively execution could be achieved using $(${cmd}) & but this is less stylish.

dg99 Over a year ago

@ShellFish Good point. I typically write my bash answers lazily and then assume that Gilles or Stephane will wander by at some later date to correct it. :)

Chris Over a year ago

Is there a nice way of doing this if the commands are long and full of parameters and quote marks?

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