subprocess.run: is it safe to combine check=true with stdout=pipe?

[...] is equivalent to:

run(..., check = True)

As it's "equivalent", does this warning also apply to run(..., check=True), i.e., should

subprocess.run(..., stdout = subprocess.PIPE, check = True)

and

subprocess.run(..., stderr = subprocess.PIPE, check = True)

Suggestion : 2

If capture_output is true, stdout and stderr will be captured. When used, the internal Popen object is automatically created with stdout=PIPE and stderr=PIPE. The stdout and stderr arguments may not be supplied at the same time as capture_output. If you wish to capture and combine both streams into one, use stdout=PIPE and stderr=STDOUT instead of capture_output.,Special value that can be used as the stdin, stdout or stderr argument to Popen and indicates that a pipe to the standard stream should be opened. Most useful with Popen.communicate().,If you ran the process with stderr=subprocess.STDOUT, stdout and stderr will be combined in this attribute, and stderr will be None.,Special value that can be used as the stderr argument to Popen and indicates that standard error should go into the same handle as standard output.

os.system
os.spawn *

>>> subprocess.run(["ls", "-l"]) # doesn 't capture output
CompletedProcess(args = ['ls', '-l'], returncode = 0)

   >>>
   subprocess.run("exit 1", shell = True, check = True)
Traceback(most recent call last):
   ...
   subprocess.CalledProcessError: Command 'exit 1'
returned non - zero exit status 1

   >>>
   subprocess.run(["ls", "-l", "/dev/null"], capture_output = True)
CompletedProcess(args = ['ls', '-l', '/dev/null'], returncode = 0,
   stdout = b 'crw-rw-rw- 1 root root 1, 3 Jan 23 16:23 /dev/null\n', stderr = b '')

Popen(["/usr/bin/git", "commit", "-m", "Fixes a bug."])

>>>
import shlex, subprocess
   >>>
   command_line = input() /
   bin / vikings - input eggs.txt - output "spam spam.txt" - cmd "echo '$MONEY'" >>>
   args = shlex.split(command_line) >>>
   print(args)['/bin/vikings', '-input', 'eggs.txt', '-output', 'spam spam.txt', '-cmd', "echo '$MONEY'"] >>>
   p = subprocess.Popen(args) # Success!

Popen(['/bin/sh', '-c', args[0], args[1], ...])

with Popen(["ifconfig"], stdout = PIPE) as proc:
   log.write(proc.stdout.read())

Suggestion : 3

Felipe 03 Nov 2018 23 Nov 2019 python3

import subprocess

subprocess.call(["ls", "-lha"])
# >>> 0(the
   return code)

import subprocess

# no Python Exception is thrown!
   subprocess.call(["./bash-script-with-bad-syntax"])
# >>> 127

subprocess.call("ls -lha", shell = True)
# returns 0(the
   return code)

import subprocess
import sys

# create two files to hold the output and errors, respectively
with open('out.txt', 'w+') as fout:
   with open('err.txt', 'w+') as ferr:
   out = subprocess.call(["ls", '-lha'], stdout = fout, stderr = ferr)
# reset file to read from it
fout.seek(0)
# save output(
   if any) in variable
output = fout.read())

# reset file to read from it
ferr.seek(0)
# save errors(
   if any) in variable
errors = ferr.read()

output
# total 20 K
# drwxrwxr - x 3 felipe felipe 4, 0 K Nov 4 15: 28 .
# drwxrwxr - x 39 felipe felipe 4, 0 K Nov 3 18: 31. .
# drwxrwxr - x 2 felipe felipe 4, 0 K Nov 3 19: 32 .ipynb_checkpoints
# - rw - rw - r--1 felipe felipe 5, 5 K Nov 4 15: 28 main.ipynb

errors
# ''
empty string

import subprocess

# unlike subprocess.call, this throws a CalledProcessError
#
if the underlying process errors out
subprocess.check_call(["./bash-script-with-bad-syntax"])

import subprocess

# errors in the created process are raised here too
output = subprocess.check_output(["ls", "-lha"], universal_newlines = True)

output
# total 20 K
# drwxrwxr - x 3 felipe felipe 4, 0 K Nov 4 15: 28 .
# drwxrwxr - x 39 felipe felipe 4, 0 K Nov 3 18: 31. .
# drwxrwxr - x 2 felipe felipe 4, 0 K Nov 3 19: 32 .ipynb_checkpoints
# - rw - rw - r--1 felipe felipe 5, 5 K Nov 4 15: 28 main.ipynb

Suggestion : 4

connect to their input/output/error pipes,Here is another output after we specified stdout=subprocess.PIPE and stderr=subprocess.PIPE just as before to set up the pipe., It offers a higher-level interface than some of the other available modules, and is intended to replace the following functions:,os.popen() does the same thing as os.system except that it gives us a file-like stream object that we can use to access standard input/output for that process. There are 3 other variants of popen that all handle the i/o slightly differently.

Popen

Popen(['/bin/sh', '-c', args[0], args[1], ...])