October 17th

Recently used PHP’s simpleXML to parse through a blogs RSS feed. The parsing worked great and it was simple and clean. Only problem was that the XML nodes that contained colons in the name were being discarded by simpleXML. Example:

<sy:updatePeriod>hourly</sy:updatePeriod>
<sy:updateFrequency>1</sy:updateFrequency>

Not sure if this is a bug, error, or what but it was causing me grief. I haven’t been able to find others on the web complaining of this but my own solution was to remove the colons and traverse accordingly. I wrote a function that takes the feed as a string and returns the string with all colons inside tag names removed.

function removeColonsFromRSS($feed) {
    // pull out colons from start tags
    // (<\w+):(\w+>)
    $pattern = '/(<\w+):(\w+>)/i';
    $replacement = '$1$2';
    $feed = preg_replace($pattern, $replacement, $feed);
    // pull out colons from end tags
    // (<\/\w+):(\w+>)
    $pattern = '/(<\/\w+):(\w+>)/i';
    $replacement = '$1$2';
    $feed = preg_replace($pattern, $replacement, $feed);
    return $feed;
}

Print Ubuntu Server IP or EC2 Public IP with Bash Script

MikeGrace

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September 19th

EC2, How to, Ubuntu

How to get EC2 public IP from command line or bash script

Recently, while helping out with the OpenPhoto project, I created a bash script that would print out the Ubuntu server’s IP address if it was not installed on Amazon’s EC2. If it is installed on EC2 it would get the publicly accessible IP address of the machine and print that out instead.

#!/bin/bash
# finding IP address and compensating for possible EC2 installation
EC2=`curl --silent --connect-timeout 1 http://169.254.169.254/latest/meta-data/public-hostname`
if [[ $EC2 != "" ]]; 
then
    IP=`echo $EC2 | sed -rn 's/ec2-(.*?)\.compute.*/\1/p' | sed 's/-/./g'`
else
    IP=`ifconfig eth0 | grep 'inet addr:' | cut -d: -f2 | awk '{ print $1}'`
fi