Why is Perl scripting used for Cisco equipment?

MAC_Addy

I recently saw a job advertised and they requite Perl scripting knowledge. I've often heard about people using Perl for Cisco (and other equipment), but have never actually researched this all the way.

I was wondering what do you actually use Perl for on cisco stuff

networker050184

Mostly to make scripts for batch changes or do audits. For instance have the script log into 1,000 devices, check the config for certain syntax and add strings of commands based on whats found. Or something as simple as pushing an ACL update to 100 devices.

MAC_Addy

Well that certainly makes sense. Wouldn't want to spend the day logging into 1,000 devices and changing a small piece of code. I appreciate it, networker!

NetworkVeteran

It can also be used to configure many similar items on the same device or to monitor many devices. E.g., check all your model xxx routers to see if they've hit or are about to hit a common fault and if so alert someone.

TCL and nowadays Python are also common choices.

There are also simpler tools where you 'record' your manual activities and they auto-convert them into scripts.

JDMurray

For organizations that use UNIX or Linux, or have devices based on UNIX or Linux, they already have Perl at their fingertips. Perl has also been well-used for sysadmin tasks for over 20 years now.

DoubleNNs

Are Perl and Python similar enough that picking up Perl scripting would be easy, coming from a Python background?

fiftyo

DoubleNNs wrote: »

Are Perl and Python similar enough that picking up Perl scripting would be easy, coming from a Python background?

Syntax wise, they are not similar. However, it would be _a lot_ easier picking perl up if you already know python. It would sort of being like learning juniper if you have a background in cisco. You know the underlying technologies, such as the protocols. But, syntax and hardware structure differ. As well one vendor bring some extra knobs to the table and vise versa.

DoubleNNs

Well I ask because I have a limited Python and Java background. So I know a little bit about coding/programming in general. I do intend on going down the Cisco route - I'm studying towards my ICND2 now.
I was more curious as to whether on the scripting side, it would be more beneficial to build up my Python skills (and possibly transition later), or simply go straight developing skills in a scripting language more commonly used w/ Cisco scripting.

JDMurray

fiftyo wrote: »

it would be _a lot_ easier picking perl up if you already know python.

print "$Just $be $prepared $to $type $a $lot $of $dollar $signs,\n";
print "and spend a lot of time debugging why your code doesn't work when you forget one.\n";

fiftyo

DoubleNNs wrote: »

Well I ask because I have a limited Python and Java background. So I know a little bit about coding/programming in general. I do intend on going down the Cisco route - I'm studying towards my ICND2 now.
I was more curious as to whether on the scripting side, it would be more beneficial to build up my Python skills (and possibly transition later), or simply go straight developing skills in a scripting language more commonly used w/ Cisco scripting.

Depends, the choice mainly comes down to preference imo. While someone who has programmed a lot in say C will prefer a language like perl, due to it's structure. But in the end, most of the time, you're trying to achieve a certain task and around atleast 80% of the cases the language wont play a huge role when it comes to system administration. I like python due to the fact I can achieve a lot without writing a huge ammount of code.
It's different if you do application programming where java(uuuggh) will be preferred due to code once, run everywhere.

print "$Just $be $prepared $to $type $a $lot $of $dollar $signs,\n";
print "and spend a lot of time debugging why your code doesn't work when you forget one.\n";

print '%s %s %s %s %s %s' % thats good to keep in mind

Same thing goes if you forget tabs during if-statements in python.

NetworkVeteran

DoubleNN, I can write code in Python, TCL, Perl, and many other languages. If you already know a modern language like Python, I would just write your Cisco scripts using Python or Ruby, unless updating/maintaining code or a particularly library required doing otherwise. Python was invented with what many see as the deficiencies in Perl and other languages squarely in mind. It's also the direction employers tend to be moving towards, as opposed to the direction they're moving away from.

UnixGuy

Or you can use BASH for simple tasks, no need to learn Perl nor Python if you want to automate simple tasks. Perl & Python are huge programming languages, and usually sysadmins know basic perl one-liners or small scripts to automate simple tasks (that can usually be accomplished using BASH).

DoubleNNs

I think after passing my CCNA I'll spend a month or so looking over some Python and/or TCL. Probably won't be using either or those on the job this early in my career tho, so I'll just do a quick overview.

About7Narwhal

I think all of the Midrange (UNIX/Linux) guys where I work have at least 1 Perl book at their desks.