Calling Python Command Using Subprocess inside a Loop

Question

The Following Command is Not Waiting for The Subprocess to Finish The Execution.

mylist = ['First','Second','Third',....., 'Nth']
for items in mylist:
        subprocess.run('googleimagesdownload --keywords "'+items+'" --size medium --limit 100  --output_directory ../../../downloads')

I Want To Execute The Above Python Script in Linux Terminal But It is Not Waiting For a Subprocess To Complete Each Iteration

for items in mylist:
        os.system('googleimagesdownload --keywords "'+items+'" --size medium --limit 100  --output_directory ../../../downloads')

The Following Python Script is Working Perfectly Fine on Windows It Waits for The Command To Execute Completely Then Move to The Next Iteration But Didn't Works on Linux Terminal

the subprocess.run() call should wait for the call to finish, does it work if you replace your function call with subprocess.run(['sleep', '1'])? — Marc
– Marc, Commented Jul 13, 2021 at 15:49
After Putting The Following Code Below Mine Now The Process Reruns After 1 SecondsNothing Else. — Muhammad Naeem
– Muhammad Naeem, Commented Jul 13, 2021 at 16:12
Why do you want to wait for each task to finish? You could download them in parallel. If your problem is that your program ends before it even finishes, you should consider using asyncio stackoverflow.com/a/63786058/277267 — Daniel F
– Daniel F, Commented Jul 13, 2021 at 17:11
Can You Please Share The Example With My Code ? with Asyncio — Muhammad Naeem
– Muhammad Naeem, Commented Jul 14, 2021 at 5:48

dawidpieciul · Accepted Answer · 2021-07-13 17:06:09Z

0

I think the simplest way for you is using subprocess.Popen(). You can use then wait() method to wait for ending of called command.

Code to show you how it works:

import subprocess
mylist = ['sleep 1']*3 # program will sleep for 3 seconds
for items in mylist:
        process = subprocess.Popen(items,shell = True)
        process.wait()
        print('waiting... ')
print('FINISH!')

Your code modified and using subprocess.Popen():

mylist = ['First','Second','Third',....., 'Nth']
for items in mylist:
        process = subprocess.Popen('googleimagesdownload --keywords "'+items+'" --size medium --limit 100  --output_directory ../../../downloads')
        process.wait()

answered Jul 13, 2021 at 17:06

dawidpieciul

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3 Comments

Muhammad Naeem Over a year ago

Still After Putting Your Modified Code, Program is Still Not Waiting for Each Iteration To Completely Execute The Command & Wait For It To End.!

dawidpieciul Over a year ago

I used to use Linux programs from google to GCP. Very often programs started running in the background and after call and pressed enter key. Next command could be passed regardless of executing previous. Maybe your Linux program is running in the background..

Muhammad Naeem Over a year ago

Then Why It is Not Working Here ? Any Other Solution ?

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