Python and peexpect module

Python peexpect module makes your automation process so simple and easy. There are some other modules like Paramiko but peexpect provides great flexibility for example suppose you wanted to remote login automatically without manual interference :


p1=pexpect.spawn('/usr/bin/ssh ' + ' -o HostKeyAlias=' + source_server_ip + ' ' + source_server_user + '@'+ source_server_ip )

now you can expect output returns as follows and handle those situation:

try:
        i=p1.expect(['password:',pexpect.TIMEOUT,pexpect.EOF,'continue connecting (yes/no)?','Host key verification failed.','Connection refused','Connection timed out'],timeout=120)

        if i==1:
                logging.error('Timeout')
                logging.debug(p1.before)
                sys.exit()
        if i==2:
                logging.error('Reached EOF')
                logging.debug(p1.before)
                sys.exit()
        if i==3:
                p1.sendline('yes')
                logging.info('RSA Key added')
                p1.expect('password:',timeout=MIN_TIMEOUT_TIME)              
               
        if i==4:
                logging.info('Host key Changed,calling  edit_known_hosts('+ip+')')
                edit_known_hosts(ip)
                logging.info(ip + " removed from known_hosts,calling Connect() again")
                Connect()        
               
        if i==5:
                logging.error('Connection refused by server')
                sys.exit()
        if i==6:
                logging.error('Connection timed out')
                sys.exit()

        logging.info('sending password:' + password)
        p1.sendline(password)              ## here you can specify password if everything went fine you are logged in to remote system.

    except Exception,e:
        print ('error:',str(e))

 you can explore more from Python Official documentation it was just a snapshot. Peexpect provides a simple and quite effective situation handling.

Note : peexpect module is not yet available for windows systems you can only use it in Linux flavors.