Getting the error message "raise CalledProcessError(retcode, cmd)" when using the cat comm-CodePudding

I'm using the package subprocess as I used before:

from subprocess import check_call, STDOUT
import os
import sys

for file in os.listdir('directory/'):
    if '1' in file:
        for file_ in os.listdir('directory/'):
            if '2' in file_:
                command = f"cat directory/file1 directory/file2 > directory/file3"
                check_call(command.split(), stdout=sys.stdout, stderr=STDOUT)

The entire error message:

cat: >: No such file or directory
cat: directory/file3: No such file or directory
Traceback (most recent call last):
  File "/home/script.py", line 12, in <module>
    check_call(command.split(), stdout=sys.stdout, stderr=STDOUT)
  File "/usr/lib64/python3.6/subprocess.py", line 311, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['cat', 'directory/file1', 'directory/file2', '>', 'directory/file3']' returned non-zero exit status 1.

When I run the command

cat directory/file1 directory/file2 > directory/file3

on Linux it works fine.

Anyone has an idea what could be the problem?

CodePudding user response：

check_call does not support shell operations like ">" you will need a sub shell if you want to do that:

import subprocess
import os

for file in os.listdir('directory/'):
    if '1' in file:
        for file_ in os.listdir('directory/'):
            if '2' in file_:
                command = f"cat directory/file1 directory/file2 > directory/file3"
                process = subprocess.Popen(command, shell=True, stdout=subprocess.PIPE)
                out, err = process.communicate()

                print("STDOUT:"   str(out))