In da Wok ……

So im making a web interface for troubleshooting mpls links for some customers, Im writing the entire thing in bash, and things were going pretty well till yesterday. ( i started on saturday). You see the first page currently has the name one customer currently with a small input form next to and a troubleshoot button next to it, Now for a Mpls vpn customer there are various ways to provide last mile connectivity, im not talking about physical connectivity but the logical PE-CE connectivity, anyways after a few basic steps of automated telnet i will end up on the last mile PE and from there i want to do a source destination ping using vrf , somewhat like this

ping vrf CUSTOMER 20.20.20.2 source 20.20.20.1 repeat 3

or i use a source interface to ping , which is pretty much the same as source ip, now 20.20.20.2 is  a variable which we get when somebody inputs it into the webpage. so actually when i send the commands the ip and interface are basically variables sent across. Which actually works fine. the issue comes up when the last mile connectivity has been temporarly given on a gre tunnel , Now in this case i need to breakdance with cat/grep/sed and get the source and destination ip of the tunnel and then send across those variables to check if that connectivity exists. I know its anal, if the tunnel ip’s dont ping then 99% the tunnel destination from the tunnel source won’t ping, but i wanted to follow proper steps in this automated troubleshooting system i was building. so the command sent across is

ping $destination source $source repeat 3

But it did’nt work, since i was pushing all output to a txt file ,  i could see that command being run on the router was

ping $destination

thats it ! , now since im no programmer, it took me some time to understand whats going on, i figured there’s a new line character being added to the $destination variable which i take after certain cat /grep/cut commands done on the output file.  so i added this to the if else command after reading about the tr -d ‘\n’ command somewhere on the internet

$dest=$(echo $dest | tr -d ‘\n’)

Still didnt work, couldnt figure it out, but then i remembered that there is also a carriage return character \r , what if that also gets added in the variable,  so next step was

$dest=$(echo $dest | tr -d ‘\r\n’)

and this time it worked, perfectly fine.

I feel like i will be never able to understand programming completely, because such kind of problems take me two days, but once i get the solution i dont care, im happy and i move forward. scripting/programming for network troubleshooting, is much more rewarding that plain network troubleshooting.

So continuing with my silly scripts here’s another one to update your status on twitter, drop it in your /usr/bin and then type bwitter and then your update and then enter, thats it. of course edit your username and password for it to work . ctrl-c closes the client. im using in xterm and typing in a lot of useless updates

#!/bin/bash

#Author::deadwait

#name::bwitter

echo type in your update
read update
curl -u username:password -d status=”$update” http://twitter.com/statuses/update.xml | grep ZZ

bwitter

I can be very lazy i guess, while reading beginning perl, available here http://www.perl.org/books/beginning-perl/   i got tired of opening a new file and typing in /usr/bin/perl and then the name, and needing it to chmod +x everytime , so i write a script to do the same for me,

so all i do is type newperl month and a file with month.plx and the necessary shebang and filename and author name is created . ofcourse i dropped it in /usr/bin for it to work anywhere. below is the script. just change the author value to your name

#!/bin/sh
#newperl.sh
author=deadwait
if [ -z $1 ]
then
echo “You have not mentioned a filename”
exit $E_NOARGS
fi
echo “building file $1.plx”
echo “#!/usr/bin/perl” > $PWD/$1.plx
echo “#$1.plx”>>$PWD/$1.plx
echo “#Author - $author” >> $PWD/$1.plx
chmod +x $1.plx
echo “Done “