[Tutor] Parsing a String

[Bryon Adams]

On 11/25/2016 05:26 PM, Bryon Adams wrote:
> Hello,
>     I have written a script that pulls certain bits of information out
> of a Cisco router's 'show version' command. The output is given in the
> assignment and it does work on several different routers (I tested 3
> different models from work). What I did seems a bit messy to me though,
> would I be able to get a second opinion here? Code in it's entirety is
> below. I did this using Python3.5.2 on Fedora 25.
>
>
> #!/usr/bin/env python3
> ################################################################
> # November 24, 2016                                            #
> #  Take the given string for 'show version' on a Cisco router  #
> #  and return the following information:                       #
> #   vendor, model, os_version, uptime, serial number           #
> #  Code should be generic and work on other versions.          #
> #                                                              #
> ################################################################
>
> sh_ver = '''
> Cisco IOS Software, C880 Software (C880DATA-UNIVERSALK9-M), Version
> 15.0(1)M4, RELEASE SOFTWARE (fc1)
> Technical Support: http://www.cisco.com/techsupport
> Copyright (c) 1986-2010 by Cisco Systems, Inc.
> Compiled Fri 29-Oct-10 00:02 by prod_rel_team
> ROM: System Bootstrap, Version 12.4(22r)YB5, RELEASE SOFTWARE (fc1)
> twb-sf-881 uptime is 7 weeks, 5 days, 19 hours, 23 minutes
> System returned to ROM by reload at 15:33:36 PST Fri Feb 28 2014
> System restarted at 15:34:09 PST Fri Feb 28 2014
> System image file is "flash:c880data-universalk9-mz.150-1.M4.bin"
> Last reload type: Normal Reload
> Last reload reason: Reload Command
> Cisco 881 (MPC8300) processor (revision 1.0) with 236544K/25600K bytes
> of memory.
> Processor board ID FTX1000038X
> 5 FastEthernet interfaces
> 1 Virtual Private Network (VPN) Module
> 256K bytes of non-volatile configuration memory.
> 126000K bytes of ATA CompactFlash (Read/Write)
> License Info:
> License UDI:
> -------------------------------------------------
> Device#   PID                   SN
> -------------------------------------------------
> *0        CISCO881-SEC-K9       FTX1000038X
> License Information for 'c880-data'
>     License Level: advipservices   Type: Permanent
>     Next reboot license Level: advipservices
> Configuration register is 0x2102
> '''
> import sys
>
> # New empty dictionary to store information.
> router_dict = {}
>
> # Get vendor, although we know it's Cisco anyway.
> if 'Cisco' in sh_ver:
>   router_dict['vendor'] = 'Cisco'
> else:
>   sys.exit('This is not a Cisco device')
>
> # Split sh ver output to a list of lines
> lines = sh_ver.split('\n')
>
> # Get the IOS version, this parses for the string 'Cisco IOS Software',
> #  in every line in 'lines.' It then splits the string stored in position
> #  0 and returns position 2 as the os version and strips off the leading
> #  space.
> router_dict['os_ver'] = [i for i in lines if 'Cisco IOS Software' in
> i][0].split(',')[2][1:]
>
> # Get the model of router using the same logic as the IOS version. The line
> #  doesn't have a nice split character so I rebuilt the string using
> spaces.
> router_dict['model'] = ' '.join([i for i in lines if 'bytes of memory'
> in i][0].split()[0:3])
>
> # Get uptime using the same logic as 'model'
> router_dict['uptime'] = ' '.join([i for i in lines if 'uptime' in
> i][0].split()[3:])
>
> # Get serial number using the logic from 'os_ver'
> router_dict['serial'] = [i for i in lines if 'Processor board ID' in
> i][0].split()[3]
>
> for i in router_dict:
>   print('{:<10} {}'.format(i, router_dict.get(i)))
>
>
>
> Thanks,
>   Bryon

So I checked out what the teacher had written. He wrapped everything in 
a for loop which makes what I have look a lot better. Relevant part 
below, nothing else changed other than I changed the name of a variable 
to make them easier to distinguish.

ver_lines = sh_ver.split('\n')

for line in ver_lines:

   if 'Cisco IOS Software' in line:
     router_dict['os_ver'] = line.split(',')[2][1:]

   if 'bytes of memory' in line:
     router_dict['model'] = ' '.join(line.split()[0:3])

   if 'uptime' in line:
     router_dict['uptime'] = ' '.join(line.split()[3:])

   if 'Processor board ID' in line:
     router_dict['serial'] = line.split()[3]