Environment variable differences when using Paramiko
Solution 1
Working with the Channel
object instead of the SSHClient
object solved my problem.
chan=ssh.invoke_shell()
chan.send('echo $PATH\n')
print (chan.recv(1024))
For more details, see the documentation
Solution 2
The SSHClient.exec_command
by default does not allocate a pseudo terminal for the session. As a consequence a different set of startup scripts is (might be) sourced (particularly for non-interactive sessions, .bash_profile
is not sourced). And/or different branches in the scripts are taken, based on an absence/presence of TERM
environment variable.
To emulate the default Paramiko behavior with the ssh
, use the -T
switch:
ssh -T myuser@host
See the ssh
man:
-T
Disable pseudo-tty allocation.
Contrary, to emulate the default ssh
behavior with Paramiko, set the get_pty
parameter of the exec_command
to True
:
def exec_command(self, command, bufsize=-1, timeout=None, get_pty=False):
Though rather than working around the issue by allocating the pseudo terminal in Paramiko, you should better fix your startup scripts to set the same PATH
for all sessions.
For that see Some Unix commands fail with "<command> not found", when executed using Python Paramiko exec_command.
Uri Goren
Linkedin: http://goren.ml/linkedin GitHub: http://goren.ml/github Vimrc: http://goren.ml/vim
Updated on June 21, 2022Comments
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Uri Goren almost 2 years
I am connecting to SSH via terminal (on Mac) and run a Paramiko Python script and for some reason, the two sessions seem to behave differently. The
PATH
environment variable is different in these cases.This is the code I run:
import paramiko ssh = paramiko.SSHClient() ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy()) ssh.connect('host', username='myuser',password='mypass') stdin, stdout, stderr =ssh.exec_command('echo $PATH') print (stdout.readlines())
Any idea why the environment variables are different?
And how can I fix it?
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Martin Prikryl over 8 yearsWhile this indeed helps, the answer fails to explain why. It's not about
Channel
vs.SSHClient
. TheSSHClient
uses theChannel
internally. The difference is that your original code uses an "exec" channel, which by default does not allocate pseudo terminal. While your new code uses a "shell" channel, which by default allocates a pseudo terminal. Using shell for executing commands is not good practice. And again, it's generally a bad practice to have your account configured to use a differentPATH
for interactive and non-interactive terminals. -
Aseem almost 6 yearsI tried your code coz exec_command did not import modules like pandas even though i have them in my ec2. Even small py files that just wrote a new file did not work with your code. how can I get back errors from above method