execute which command over ssh in python script

Question

I'm trying to run the command which solsql over SSH in a Python script.

I think the problem is in the ssh command and not the Python part, but maybe it's both.

I tried

subprocess.check_output("ssh root@IP which solsql",
    stderr=subprocess.STDOUT, shell=True)

but I get an error.

I tried to run the command manually:

ssh root@{server_IP}" which solsql"

and I get a different output.

On the server I get the real path (/opt/solidDB/soliddb-6.5/bin/solsql) but over SSH I get this:

which: no solsql in
(/usr/lib64/qt-3.3/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin)

Answer 1

I think what your looking for is something like paramiko. An example of how to use the library and issue a command to the remote system.

import base64
import paramiko
key = paramiko.RSAKey(data=base64.b64decode(b'AAA...'))
client = paramiko.SSHClient()
client.get_host_keys().add('ssh.example.com', 'ssh-rsa', key)
client.connect('ssh.example.com', username='THE_USER', password='THE_PASSWORD')
stdin, stdout, stderr = client.exec_command('which solsql')
for line in stdout:
    print('... ' + line.strip('\n'))
client.close()

Answer 2

When you run a command over SSH, your shell executes a different set of startup files than when you connect interactively to the server. So the fundamental problem is really that the path where this tool is installed is not in your PATH when you connect via ssh from a script.

A common but crude workaround is to force the shell to read in the file with the PATH definition you want; but of course that basically requires you to know at least where the correct PATH is set, so you might as well just figure out where exactly the tool is installed in the first place anyway.

ssh server '. .bashrc; type -all solsql'

(assuming that the PATH is set up in your .bashrc; and ignoring for the time being the difference between executing stuff as yourself and as root. The dot and space before .bashrc are quite significant. Notice also how we use the POSIX command type rather than the brittle which command which should have died a natural but horrible death decades ago).

If you have a good idea of where the tool might be installed, perhaps instead do

subprocess.check_output(['ssh', 'root@' + ip, '''
    for path in /opt/solidDB/*/bin /usr/local/bin /usr/bin; do
         test -x "$path/solsql" || continue
         echo "$path"
         exit 0
     done
     exit 1'''])

Notice how we also avoid the (here, useless) shell=True. Perhaps see also Actual meaning of 'shell=True' in subprocess

Answer 3

First, you need to debug your error.

Use the code like this:

command = "ssh root@IP which solsql"

try:
    retult = subprocess.check_output(command,shell=True,stderr=subprocess.STDOUT)
except subprocess.CalledProcessError as e:
    raise RuntimeError("command '{}' return with error (code {}): {}".format(e.cmd, e.returncode, e.output))

print ("Result:", result)

It will output error message to you, and you'll know what to do, for example, ssh could have asked for a password, or didn't find your key, or something else.