Question

Part of my code:

import subprocess
import logging
logging.basicConfig(filename='daily_backup_run.log', level=logging.DEBUG)

try:
  git_command = subprocess.Popen("git status", shell="true")
  git_status_output = git_command.stdout.readline()
except subprocess.CalledProcessError, e:
  git_status_output = e.output
logging.debug(' Output of git status: ' + git_status_output)
exit()

When I attempt to run this, my output is:

[~/experiment_folder]# python git.py
Traceback (most recent call last):
  File "git.py", line 35, in ?
    except subprocess.CalledProcessError, e:
AttributeError: 'module' object has no attribute 'CalledProcessError'
fatal: Not a git repository (or any of the parent directories): .git

I am not concerned with the Python errors at the moment, but I need all output sent by git to go into the daily_backup_run.log – even the fatal: Not a repo error. How do I ensure this?

Answer 1

From the Subprocess module documentation:

stdin, stdout and stderr specify the executed program’s standard input, standard output and standard error file handles, respectively. Valid values are PIPE, an existing file descriptor (a positive integer), an existing file object, and None. PIPE indicates that a new pipe to the child should be created.

You can modify the code as follows:

# working dir in which git [command] is called
cwd = '/path/to/git/repository' 

p = subprocess.Popen("git status", shell="true", cwd=cwd,
                     stdout=subprocess.PIPE, stderr=subprocess.PIPE)
outdata, errdata = p.communicate()

logging.debug('Output of git status: {}. Error data if any: {}'
              .format(outdata, errdata))