ssh through python script

Question

this is how my python script looks like

import os
command = 'ssh testServer'
os.system(command)

it gives me following error

[Sun Aug 17 11:07:30 Adam@testServer:~/] $ python test.py
ld.so.1: ssh: fatal: relocation error: file /usr/bin/ssh: symbol SUNWcry_installed: referenced symbol not found
Killed

Ssh command works fine when I execute it from command line. Only when I try it from within a python script using either os/subprocess module, it complains with the above error.

The problem seems to be related to the LD_LIBRARY_PATH environment variable. Could you post the output of ldd /usr/bin/ssh and echo $LD_LIBRARY_PATH both from the command line and from a python system call. — Andrew Johnson
– Andrew Johnson, Commented Aug 17, 2014 at 18:38
libsocket.so.1 =>/lib/libsocket.so.1 libnsl.so.1 =>/lib/libnsl.so.1 libz.so.1 =>/opt/svn/current/lib/libz.so.1 libz.so.1 (SUNW_1.1) => (version not found) libcrypto.so.0.9.7 => /usr/sfw/lib/libcrypto.so.0.9.7 libgss.so.1 =>/usr/lib/libgss.so.1 libc.so.1 =>/lib/libc.so.1 libmp.so.2 =>/lib/libmp.so.2 libmd.so.1 =>/lib/libmd.so.1 libscf.so.1 =>/lib/libscf.so.1 libcmd.so.1 =>/lib/libcmd.so.1 libdoor.so.1 =>/lib/libdoor.so.1 libuutil.so.1 => /lib/libuutil.so.1 libgen.so.1 =>/lib/libgen.so.1 libcrypto_extra.so.0.9.7 => /usr/sfw/lib/libcrypto_extra.so.0.9.7 libm.so.2 =>/lib/libm.so.2 — nick01
– nick01, Commented Aug 17, 2014 at 18:48

Devarsh Desai · Accepted Answer · 2014-08-17 18:32:28Z

1

You shouldn't use os.system, you should use a subprocess:

Like in your case:

 bshCmd = "ssh testServer"
 import subprocess
 process = subprocess.Popen(bshCmd.split(), stdout=subprocess.PIPE)
 output = process.communicate()[0]

Please let me know if you have any questions!

answered Aug 17, 2014 at 18:32

Devarsh Desai

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11 Comments

nick01 Over a year ago

Hello @cartridgemeadow.. I used both os/subprocess and see the same result. I specified this in my question originally. Just to confirm I used your code but see the same error again

Devarsh Desai Over a year ago

hmm...@user2812714, could you try running "unset $LD_LIBRARY_PATH" before you run ssh; and before you unset it, be SURE to echo it and copy it's contents from bash into a text file, so that you could reset it later

Devarsh Desai Over a year ago

also, if you run "ssh testServer" from bash, does it work? if it does, then this is a python issue that has to do with property settings and we could find a work around!

nick01 Over a year ago

I get this when I try to unset unset $LD_LIBRARY_PATH -bash: unset: `/opt/svn/current/lib': not a valid identifier

nick01 Over a year ago

yes as mentioned in the question, it does work when I execute it from bash.

|

Andrew Johnson · Accepted Answer · 2014-08-17 19:24:46Z

1

So your ssh relies on a library that is located in /opt/svn/current/lib: "libz.so.1 =>/opt/svn/current/lib/libz.so.1 libz.so.1 (SUNW_1.1)". It finds this library by looking at the environment variable LD_LIBRARY_PATH. This variable is not preserved by the os.system call in python.

import os
import subprocess
command = 'ssh testServer'
subprocess.Popen(command, shell=True, env=os.environ)

edited Aug 17, 2014 at 19:24

answered Aug 17, 2014 at 19:10

Andrew Johnson

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Comments

user590028 · Accepted Answer · 2014-08-17 18:46:14Z

0

Have you considered using an ssh automation package instead? Something like https://pypi.python.org/pypi/ssh/1.7.8

answered Aug 17, 2014 at 18:46

user590028

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Kasravnd · Accepted Answer · 2014-08-17 18:54:09Z

0

The os.system has many problems and subprocess is a much better way to executing unix command. Use This recipe:

import subprocess
ssh = subprocess.Popen(["ssh", "%s" % HOST, COMMAND],
                           shell=False,
                           stdout=subprocess.PIPE,
                           stderr=subprocess.PIPE)

edited Aug 17, 2014 at 18:54

answered Aug 17, 2014 at 18:38

Kasravnd

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2 Comments

nick01 Over a year ago

I used both subprocess/os as mentioned in the question. I still see the same issue

Kasravnd Over a year ago

see this link python-for-system-administrators.readthedocs.org/en/latest/…

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