如何使用相对引用使用子进程运行复杂的python命令？

Question

I am trying to execute this command using Python:

findSyntax = "find . -maxdepth 2 -name '.config' | cpio -updm ../test1/"
subprocess.Popen(findSyntax.split(' '))

But this command just would not work. When I execute this command, it will start listing all the files (not just .config) under the . directory beyond the maxdepth 2... which is a long list.

What am I missing here! Can someone point it out? Thanks.

NOTE: I've tried running subProcess.run as well with same results. I was able to get just the find part working using os.system() command.

EDIT: I just wanted to clarify that this command will copy the files found with the exact directory structure intact to the new location (creating subdirectories if necessary). I've tried this command on bash terminal, and it works fine. But I couldn't get it to work with Python.

EDIT2: So, the whole command works with os.system() , but I couldn't figure out how to make it work with subprocess . os.system() is supposed to be deprecated, so I would be very interested in figuring out the solution using subprocess instead.

Answer 1

Please look at this good answer and this also helps

But in essence, you can't use your above subprocess command with a pipe.

Lets run through the simple example of getting all py files in the current directory: ( ls | grep py )
This is broken:

import subprocess
subprocess.call(['ls', '|', 'grep', 'py'])

Because subprocess does only one process at a time, and by piping you are really creating 2 processes.

The simple but limited (to platform) way is to use os.system

import os
os.system('ls | grep py')

This literally just passes a shell command to the system to execute.

However, you should do it with subprocess by defining your pipes:

# Get all files and pass the stdout to a pipe
p1 = subprocess.Popen(['ls'], stdout=subprocess.PIPE)
# then pass that pipe to another process as stdin and do part 2
output = subprocess.check_output(['grep', 'py'], stdin=p1.stdout)
print(output)

So, a copy paste for your example:

import subprocess
p1 = subprocess.Popen("find . -maxdepth 2 -name '.config'".split(), stdout=subprocess.PIPE)
output = subprocess.check_output("cpio -updm ../test1/".split(), stdin=p1.stdout)

Or with os :

os.system("find . -maxdepth 2 -name '.config' | cpio -updm ../test1/")