Python command line loop

Question

I'm running a mrjob python script, and in the command line I can pass the number of cores for the system to use.

python example_script.py --num-cores 5

I'm looking to run the script for n number of cores for beach marking performance test. IE: I want to run it for 1 core, 2 core etc.

Is there anyway I can write a loop directly into the command line rather then having to write out the whole command n number of times?

I want to test the performance of the script across n number of cores — F.D, Apr 27 '18 at 14:26
But why do you want to pass the number of cores that way? Why not a simple integer? That's what a number of cores is, not a range. — mafrasi2, Apr 27 '18 at 14:29
Possible duplicate of [Bash 'for' loop syntax?](https://stackoverflow.com/questions/6854118/bash-for-loop-syntax) — munk, Apr 27 '18 at 14:30
@mafrasi2 ok, perhaps I wasn't clear. I updated the question there and hope it's clearer now? — F.D, Apr 27 '18 at 14:32

score 1 · Accepted Answer · answered Apr 27 '18 at 14:39

As in you want to lunch 4 isntances of mrjob each with increasing number of cores?

i.e.

python mrjob.py --num-core-instances=1
python mrjob.py --num-core-instances=2
python mrjob.py --num-core-instances=3
python mrjob.py --num-core-instances=4

In that case I don't think you can. You can make a script that lunches those for you though.

import subprocess
for i in range(1,5):
    subprocess.Popen(["start","cmd","/k","python","mrjob.py","--num-core-instance="+i],shell=True)

score 1 · Answer 2 · answered Apr 27 '18 at 14:42

1

Is this what you want to do ?

for i in {1..10} ; do python example_script.py --num-cores $i ; done ;

It is a bash for loop.

answered Apr 27 '18 at 14:42

cdrom

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Python command line loop

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