CODEWITHSUNDEEP
pythonshellsubprocess
avelampudi
avelampudi

Reputation: 326

subprocess.Popen shell=True to shell=False

I know that it is bad practice to use shell=True for subprocesses. However for this line of code, I'm not sure how to execute it with shell=False

subprocess.Popen('candump -tA can0 can1 >> %s' %(file_name), shell=True)

Where the command I want to run is:

candump -tA can0 can1 >> file_name

Where file_name is /path/to/file.log

Upvotes: 5

Views: 2637

Answers (2)

kanaka
kanaka

Reputation: 73099

Only shell mode supports inline piping operators so you'll need to do the redirection manually. Also, you'll need to split your command line into individual arguments which you can either do manually or have the shlex module do for you:

subprocess.Popen(shlex.split('candump -tA can0 can1'), stdout=open(file_name, 'ab'))

Upvotes: 0

ShadowRanger
ShadowRanger

Reputation: 155363

You can't directly use piping in the command the way you do with shell=True, but it's easy to adapt:

with open(file_name, 'ab') as outf:
    proc = subprocess.Popen(['candump', '-tA', 'can0', 'can1'], stdout=outf)

That opens the file at the Python level for binary append, and passes it as the stdout for the subprocess.

Upvotes: 8

Related Questions