Call in python return code status only

Question

I have the following code in python:

i = call(["salt-cloud", "-m", fileName, "--assume-yes"])
print (i)

i is always 0, because the operation is finished.

The problem is that I want to get the output of this operation. In our case:

window:
    ----------
    Error:
        ----------
        Not Deployed:
            Failed to start Salt on host window

is the output of running salt-cloud -m fileName --assume-yes, and it is an indication that error raised in this process, and I want to know it.

How can I achieve it in Python?

you can use subprocess.Popen

Hackaholic
– Hackaholic

2015-03-30 13:24:15 +00:00
Commented Mar 30, 2015 at 13:24 — Hackaholic
– Hackaholic, Commented Mar 30, 2015 at 13:24

Padraic Cunningham · Accepted Answer · 2015-03-30 13:51:54Z

3

Use check_output and catch a CalledProcessError which will be raised for any non-zero exit status:

from subprocess import check_output, CalledProcessError    

try:
    out = check_call(["salt-cloud", "-m", fileName, "--assume-yes"]) 
    print(out)   
except CalledProcessError as e:
    print(e.message)

If you are using python < 2.7 you will need Popen, check_call and check_output were added in python 2.7:

from subprocess import Popen, PIPE

p = Popen(["salt-cloud", "-m", filename, "--assume-yes"],stderr=PIPE,stdout=PIPE)

out, err = p.communicate()

print( err if err else out)

edited Mar 30, 2015 at 13:51

answered Mar 30, 2015 at 13:31

Padraic Cunningham

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5 Comments

MIDE11 Over a year ago

But it returns 0, even if the process is failed (like in my example - window was not deployed, but code 0 was returned)

Padraic Cunningham Over a year ago

Then it is a normal exit status. try check_output. Does it ever raise a non-zero exit status?

MIDE11 Over a year ago

I try the following: ` try: from subprocess import check_output except Exception as e: print e` and it gives me the following error:cannot import name check_output

Padraic Cunningham Over a year ago

are you using python2.6?

Padraic Cunningham Over a year ago

then use the second part of the answer

maahl · Accepted Answer · 2015-03-30 13:26:07Z

2

Assuming you're using subprocess.call, you might want to take a look at subprocess.check_output(), which returns the output of the subprocess as a byte string.

answered Mar 30, 2015 at 13:26

maahl

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3 Comments

MIDE11 Over a year ago

Should I use it this way: import subprocess subprocess.check_output(["salt-cloud", "-m", fileName, "--assume-yes"])

maahl Over a year ago

You'll have to get the output in a variable if you want to use it. output = subprocess.check_output(...)

MIDE11 Over a year ago

I try the following: ` try: from subprocess import check_output except Exception as e: print e` and it gives me the following error:cannot import name check_output

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