Python ssh paramiko to detect failed command

Question

I am using paramiko to establish ssh session and send commands to the server.

Few of the commands are not successfully executed. How do i detect those commands are failed to execute and terminate python code. Below is the code what I am trying :

remote_conn_pre = paramiko.SSHClient()
remote_conn_pre.set_missing_host_key_policy(
     paramiko.AutoAddPolicy())
remote_conn_pre.connect(host, username=username, password=password, look_for_keys=False, allow_agent=False)
print "SSH connection established to %s" % host
# Use invoke_shell to establish an 'interactive session'
remote_conn = remote_conn_pre.invoke_shell()
remote_conn.send("\n")
remote_conn.send("scope org engg\n")
remote_conn.send("\n")
remote_conn.send("show service-profile")
if remote_conn.recv_ready():
   details = remote_conn.recv(5000)
remote_conn.close()

Details output:

  servera# scope org engg 
  Error: Managed object does not exist # org engg is not exist that the reason we are getting this error
  servera#
  servera# show service-profile

  % Incomplete Command at '^' marker # since the above command is failed but paramiko does not able to identify it is moving to second command execution . There is no org engg so that the reason i am getting incomplete command warning.

Note: This is not a shell so I have to use shell invoke here.

Please help how to detect not successful ran command and terminate the python program.

paramiko cannot tell you if the command failed or not. you have to parse the output all by yourself. — pynexj
– pynexj, Commented May 6, 2017 at 12:23

Laurent LAPORTE · Accepted Answer · 2017-05-06 06:18:30Z

-1

One way to do that is:

create a small bash script locally which can handle errors,
copy the script in the remote server using scp,
run the script and catch it's output,
parse the output to see if an error occurs.

Here is an example of bash script:

#!/bin/bash

function error() {
    local parent_line_no="$1"
    local message="$2"
    local code="${3:-1}"
    if [[ -n "$message" ]] ; then
        echo "Error on or near line ${parent_line_no}: ${message}; exiting with status ${code}"
    else
        echo "Error on or near line ${parent_line_no}; exiting with status ${code}"
    fi
    exit "${code}"
}
trap 'error ${LINENO}' ERR

# your commands here...

answered May 6, 2017 at 6:18

Laurent LAPORTE

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4 Comments

asteroid4u Over a year ago

remote server is not unix/linux based server this will work?

Laurent LAPORTE Over a year ago

@asteroid4u: Yes, this is a bash script.

pynexj Over a year ago

the OP's remote login shell does not look like bash.

asteroid4u Over a year ago

yes remote server does not bash shell its kind of of switch

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