Develop Reference

How to run write adb command result on host system not an emulator from python script

The following command works fine when I run it through Terminal.
adb -s 192.168.100.101:5555 shell tcpdump -nnvvettU -s 0 -i eth1 > dump.txt
But when I try to run it from python script it try to write on emulator which fails as follow:
#Python script:
cmd_str = "adb -s 192.168.100.101:5555 shell tcpdump -nnvvettU -s 0 -i eth1 > dump.txt"
cmd = cmd_str.split()
call(cmd)
#Error:
/system/bin/sh: can't create dump.txt: Read-only file system
so how can I write the file on the host system not an emulator in python script?

How to run the bash command as a system user without giving that user the right to run commands as any user

I have written a python script which includes this line:
response = subprocess.check_output(['/usr/bin/sudo /bin/su - backup -c "/usr/bin/ssh -q -o StrictHostKeyChecking=no %s bash -s" <<\'EOF\'\nPATH=/usr/local/bin:$PATH\nmvn --version|grep -i Apache|awk \'{print $3}\'|tr -d \'\n\'\nEOF' % i], shell=True)
This is in a for loop that goes through a list of hostnames and each one I want to check the result of the command on it. This works fine when I run it myself, however, this script is to be run by a system user (shinken - a nagios fork) and at that point I hit an issue.
shinken ALL=(ALL) NOPASSWD: ALL
However, I wanted to restrict the user to only allow it to run as the backup user:
shinken ALL=(backup) NOPASSWD: ALL
But when I run the script I get:
sudo: no tty present and no askpass program specified
I have read around this and tried a few things to fix it. I tried adding -t to my ssh command, but that didn't help. I believe I should be able to run the command with something similar to:
response = subprocess.check_output(['/usr/bin/sudo -u backup """ "/usr/bin/ssh -q -o StrictHostKeyChecking=no %s bash -s" <<\'EOF\'\nPATH=/usr/local/bin:$PATH\njava -version|grep -i version|awk \'{print $3}\'|tr -d \'\n\'\nEOF""" ' % i], shell=True)
But then I get this response:
subprocess.CalledProcessError: Command '['/usr/bin/sudo -u backup """ "/usr/bin/ssh -q -o StrictHostKeyChecking=no bamboo-agent-01 bash -s" <<\'EOF\'\nPATH=/usr/local/bin:$PATH\njava -version|grep -i version|awk \'{print $3}\'|tr -d \'\n\'\nEOF""" ']' returned non-zero exit status 1
If I run the command manually I get:
sudo: /usr/bin/ssh: command not found
Which is strange because that's where it lives.... I've no idea if what I'm trying is even possible. Thanks for any suggestions!

As for sudo:
shinken ALL=(backup) NOPASSWD: ALL
...only works when you switch directly from shinken to backup. You aren't doing that here. sudo su - backup is telling sudo to switch to root, and to run the command su - backup as root. Obviously, then, if you're going to use sudo su (which I've advised against elsewhere), you need your /etc/sudoers configuration to support that.
Because your /etc/sudoers isn't allowing direct the switch to root you're requesting, it's trying to prompt for a password, which requires a TTY, which is thus causing a failure.
Below, I'm rewriting the script to switch directly from shinken to backup, without going through root and running su:
As for the script:
import subprocess
remote_script='''
PATH=/usr/local/bin:$PATH
mvn --version 2>&1 | awk '/Apache/ { print $3 }'
'''
def maven_version_for_host(hostname):
# storing the command lets us pass it when constructing a CalledProcessError later
# could move it directly into the Popen creation if you don't need that.
cmd = [
'sudo', '-u', 'backup', '-i', '--',
'ssh', '-q', '-o', 'StrictHostKeyChecking=no', str(hostname),
'bash -s' # arguments in remote-command position to ssh all get concatenated
# together, so passing them as one command aids clarity.
]
proc = subprocess.Popen(cmd,
stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
response, error_string = proc.communicate(remote_script)
if proc.returncode != 0:
raise subprocess.CalledProcessError(proc.returncode, cmd, error_string)
return response.split('\n', 1)[0]

Running interactive commands in docker in Python subprocess

When I use docker run in interactive mode I am able to run the commands I want to test some python stuff.
root#pydock:~# docker run -i -t dockerfile/python /bin/bash
[ root#197306c1b256:/data ]$ python -c "print 'hi there'"
hi there
[ root#197306c1b256:/data ]$ exit
exit
root#pydock:~#
I want to automate this from python using the subprocess module so I wrote this:
run_this = "print('hi')"
random_name = ''.join(random.SystemRandom().choice(string.ascii_uppercase + string.digits) for _ in range(20))
command = 'docker run -i -t --name="%s" dockerfile/python /bin/bash' % random_name
subprocess.call([command],shell=True,stderr=subprocess.STDOUT)
command = 'cat <<\'PYSTUFF\' | timeout 0.5 python | head -n 500000 \n%s\nPYSTUFF' % run_this
output = subprocess.check_output([command],shell=True,stderr=subprocess.STDOUT)
command = 'exit'
subprocess.call([command],shell=True,stderr=subprocess.STDOUT)
command = 'docker ps -a | grep "%s" | awk "{print $1}" | xargs --no-run-if-empty docker rm -f' % random_name
subprocess.call([command],shell=True,stderr=subprocess.STDOUT)
This is supposed to create the container, run the python command on the container and exit and remove the container. It does all this except the command is run on the host machine and not the docker container. I guess docker is switching shells or something like that. How do I run python subprocess from a new shell?

It looks like you are expecting the second command cat <<... to send input to the first command. But the two subprocess commands have nothing to do with each other, so this doesn't work.
Python's subprocess library, and the popen command that underlies it, offer a way to get a pipe to stdin of the process. This way, you can send in the commands you want directly from Python and don't have to attempt to get another subprocess to talk to it.
So, something like:
from subprocess import Popen, PIPE
p = Popen("docker run -i -t --name="%s" dockerfile/python /bin/bash", stdin=PIPE)
p.communicate("timeout 0.5 python | head -n 500000 \n" % run_this)
(I'm not a Python expert; apologies for errors in string-forming. Adapted from this answer)

You actually need to spawn a new child on the new shell you are opening.So after docker creation run docker enter or try the same operation with pexpect instead of subprocess.`pexpect spawns a new child and that way you can send commands.

Subprocess calls acting differently in shell and interpretor

When I run the following commands in Python interpreter, all is good, but fail when run as a script. Somehow the opened tunnel is not recognized. Any pointers will be appreciated.
Interpreter:
gateway = subprocess.Popen("ssh -N sshgw", shell=True)
scp_prod = "scp -r server:/NFS/{0} .".format(filePath)
subprocess.call(scp_prod, shell=True)
gateway.kill()
Script:
try:
gateway = subprocess.Popen("ssh -N sshgw", shell=True)
scp_prod = "scp -r server:/NFS/{0} .".format(filePath)
subprocess.call(scp_prod, shell=True)
finally:
gateway.kill()

python - running ssh/rsync commands in a script called via crontab

I have a very strange issue that I can't seem to figure out.
When I execute a python script containing the following lines while inside a SSH terminal (putty), it works fine. But the moment I run the script via crontab or even nohup python myscript >/dev/null 2>&1& it doesn't seem to execute these commands.
subprocess.call('rsync -avr /path/to/folder/. --include "delta.*" --exclude "*" -e "ssh -o StrictHostKeyChecking=no -i /path/to/key.pem" ec2-user#'+server+':/path/to/folder/', shell=True)
local('ssh -t -o StrictHostKeyChecking=no -i /path/to/key.pem ec2-user#'+server+' "sudo /usr/bin/indexer -c /path/to/sphinx.conf --merge main delta --rotate"')
Basically all the above is doing is syncing a folder with new sphinx search engine updates to a remote server, then the second line runs a remote ssh command to force the search engine to rotate updates into production.
I do have fabric installed (hence the local command) but to avoid having to fab a second file I was hoping a single line of code could allow me to execute sudo commands on a remote server.
Can someone help me out?

I found the answer, for ssh commands in a script run in the background, you need to to have -t -t to force a pseudo terminal.
Reference:
Pseudo-terminal will not be allocated because stdin is not a terminal