client = paramiko.SSHClient()
stdin, stdout, stderr = client.exec_command(command)
Is there any way to get the command return code?
It's hard to parse all stdout/stderr and know whether the command finished successfully or not.
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4 Answers
A much easier example that doesn't involve invoking the "lower level" channel class directly (i.e. - NOT using the client.get_transport().open_session() command):
import paramiko
client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
client.connect('blahblah.com')
stdin, stdout, stderr = client.exec_command("uptime")
print stdout.channel.recv_exit_status() # status is 0
stdin, stdout, stderr = client.exec_command("oauwhduawhd")
print stdout.channel.recv_exit_status() # status is 127
2 Comments
Scott Prive
What's nice about this example is capturing not just EXIT (like the question asks), but demonstrating you can still get STDOUT and STDERR. Years ago I was misled by Paramiko's anemic example codebase (no disrespect), and to get EXIT I resorted to low-level transport() calls. transport() seemed to force you to "pick one" (which may not be true, but lack of examples and tutorial docs led me to believe that)...
Martin Prikryl
While you are correct about
recv_exit_status, you cannot use it this way, as the code may deadlock. You have to consume the command output, while waiting for the command to finish. See Paramiko ssh die/hang with big output.SSHClient is a simple wrapper class around the more lower-level functionality in Paramiko. The API documentation lists a recv_exit_status() method on the Channel class.
A very simple demonstration script:
import paramiko
import getpass
pw = getpass.getpass()
client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.WarningPolicy())
client.connect('127.0.0.1', password=pw)
while True:
cmd = raw_input("Command to run: ")
if cmd == "":
break
chan = client.get_transport().open_session()
print "running '%s'" % cmd
chan.exec_command(cmd)
print "exit status: %s" % chan.recv_exit_status()
client.close()
Example of its execution:
$ python sshtest.py
Password:
Command to run: true
running 'true'
exit status: 0
Command to run: false
running 'false'
exit status: 1
Command to run:
$
2 Comments
Patrick
This is a bad solution. See @apdastous' answer below, it's much better.
Martin Prikryl
While you are correct about
recv_exit_status, you cannot use it this way, as the code may deadlock. You have to consume the command output, while waiting for the command to finish. See Paramiko ssh die/hang with big output.Thanks for JanC, I added some modification for the example and tested in Python3, it really useful for me.
import paramiko
import getpass
pw = getpass.getpass()
client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.WarningPolicy())
#client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
def start():
try :
client.connect('127.0.0.1', port=22, username='ubuntu', password=pw)
return True
except Exception as e:
#client.close()
print(e)
return False
while start():
key = True
cmd = input("Command to run: ")
if cmd == "":
break
chan = client.get_transport().open_session()
print("running '%s'" % cmd)
chan.exec_command(cmd)
while key:
if chan.recv_ready():
print("recv:\n%s" % chan.recv(4096).decode('ascii'))
if chan.recv_stderr_ready():
print("error:\n%s" % chan.recv_stderr(4096).decode('ascii'))
if chan.exit_status_ready():
print("exit status: %s" % chan.recv_exit_status())
key = False
client.close()
client.close()
1 Comment
kten
do we get any error message -if any - in chan.recv_stderr_ready()?. Does chan.recv_stderr(4096).decode('ascii') this return a message text?
In my case, output buffering was the problem. Because of buffering, the outputs from the application doesn't come out non-blocking way. You can find the answer about how to print output without buffering in here: Disable output buffering. For short, just run python with -u option like this:
> python -u script.py
