Python Executing remote ssh command

Question

I'm writing a python nagios check to check the timestamp of a file the last time it was updated, however I need to check two separate hosts in my script so I want to use a remote ssh command to return the timestamp to stdout and use that to make sure a script has completed within the last 24 hours because when the script completes it touches a file.

When I run the command from command prompt it works however when I run it from my python code it doesn't return the output back to my program.

Grants-MacBook-Pro:test GrantZukel$ ssh ubuntu@hostname sudo ls -la /home/ubuntu/ | grep code_regen_complete

The authenticity of host 'ec2-54-144-160-238.compute-1.amazonaws.com (54.144.160.238)' can't be established.

RSA key fingerprint is hidden.

Are you sure you want to continue connecting (yes/no)? yes

Failed to add the host to the list of known hosts (/Users/GrantZukel/.ssh/known_hosts).

-rw-r--r-- 1 root   root       0 Jan 29 17:23 code_regen_complete

Grants-MacBook-Pro:test GrantZukel$

The python is :

def get_code_time(): 
    p = subprocess.Popen(['ssh','ubuntu@hostname', '"sudo ls -la /home/ubuntu/ | grep code_regen_complete"'], stdout=subprocess.PIPE)
    out, err = p.communicate()
    m = re.search('\d{4}-\d{2}-\d{2}\s+\d{2}:\d{2}:\d{2}', out)
    return m.group(0)

however when I use debugger the out or err vars are completely empty. Any ideas?

unrelated, but if you log in as ubuntu, why do you need to sudo to list /home/ubuntu? — njzk2
– njzk2, Commented Jan 29, 2015 at 19:24
and why don't you ls -l /home/ubuntu/code_regen_complete directly? — njzk2
– njzk2, Commented Jan 29, 2015 at 19:26

Kasravnd · Accepted Answer · 2015-01-29 19:24:32Z

2

You need to pass shell=True in your command :

p = subprocess.Popen(['ssh','ubuntu@hostname', '"sudo ls -la /home/ubuntu/ | grep code_regen_complete"'], stdout=subprocess.PIPE,shell=True)

answered Jan 29, 2015 at 19:24

Kasravnd

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4 Comments

Grant Zukel Over a year ago

Thanks this worked I still had to modify a few things but this ultimately is what helped thanks.

Grant Zukel Over a year ago

one more qeustion tho

Grant Zukel Over a year ago

sudo ssh ubuntu@hosts sudo git log -1 --date=iso | grep ^Date: | awk '{print $2','$3, $4}' how do i execute that command against /var/www/vhosts/webdirectory

Grant Zukel Over a year ago

local_repo_date = compare_codebase("sudo ssh ubuntu@hostname 'cd /var/www/vhosts/bazumedia.com/; sudo git log -1 --date=iso | grep ^Date'") I figured it out nvm

ncocacola · Accepted Answer · 2015-01-29 19:38:24Z

1

Get rid of the double-quotes around the ls command:

p = subprocess.Popen(['ssh','ubuntu@hostname', 'sudo ls -la /home/ubuntu/code_regen_complete'], stdout=subprocess.PIPE)

You might also want to try Fabric.

answered Jan 29, 2015 at 19:38

ncocacola

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