CODEWITHSUNDEEP
pythondockerpopen
cat
cat

Reputation: 1

How do you use a python variable in popen()?

Im trying to record docker stats for every file in the mydata directory. For example if one of the files is names piano.txt I would like the output file to be piano_stuff.txt. This is what I have so far:

import subprocess
import signal
import os 

for file_name in os.listdir('mydata'):
    data_txt = "./" + file_name.split(".")[0] + "_stuff.txt"
    dockerStats = subprocess.Popen("docker stats  --format {{.MemUsage}} >> ${data_txt}", shell=True)
    os.killpg(os.getpgid(dockerStats.pid), signal.SIGTERM)

Upvotes: 0

Views: 59

Answers (1)

chepner
chepner

Reputation: 532043

Don't use shell=True. Open the file locally, and pass the file object as the stdout argument. You can also use the --no-stream option to have the command exit after producing one line of output, rather than asynchronously trying to kill the process as soon as possible. (You might get multiple lines of output, or you might get none, depending on when the OS schedules the Docker process to run.)

with open(data_txt, "a") as f:
    subprocess.run(["docker", "stats", "--format", "{{.MemUsage}}", "--no-stream"], stdout=f)

Upvotes: 1

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