This example is using;

• Amazon Linux (as of 2012-03)
• nginx-0.8.54-1.4.amzn1.x86_64
• jetty6-6.1.14-1.jpp5.noarch from jpackage.org

Perform the following steps:

1. Install and configure nginx to proxy all requests to localhost port 8080.

       location / {
                proxy_pass   http://127.0.0.1:8080;
        }

2. Install and configure jetty6, using all default options.
3. Configure nginx to set the proxy header values for X-Forwarded-For

       location / {
                proxy_set_header X-Real-IP       $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header Host            $host;
                proxy_pass   http://127.0.0.1:8080;
        }

4. Configure Jetty to log the X-Forwarded-For IP in /etc/jetty6/jetty.xml under the RequestLog section


...
<Set name="LogTimeZone">GMT</Set>
<Set name="PreferProxiedForAddress">true</Set>
</New>
...


5. Once that is complete, restart both nginx and jetty to test.

sudo /etc/init.d/nginx restart
sudo /etc/init.d/jetty6 restart

Try this to list the top 20 space offenders:

SELECT engine, concat( table_schema, '.', table_name ) table_name,
concat( round( data_length / ( 1024 *1024 ) , 2 ) , 'M' ) data_length,
concat( round( index_length / ( 1024 *1024 ) , 2 ) , 'M' ) index_length,
concat( round( round( data_length + index_length ) / ( 1024 *1024 ) , 2 ) , 'M' ) total_size
FROM information_schema.TABLES
ORDER BY ( data_length + index_length ) DESC LIMIT 20

Taken from a comment on the mysql developer docs site: http://dev.mysql.com/doc/refman/5.1/en/tables-table.html

I find it easy to start with ls when I don’t need to recurse into a directory tree as that is a command that I use often. This often turns into a process such as this:

for dir in $(ls)
do
  echo ${dir}
done

Now the above method typically does not work for me. I have an alias setup to print out pretty colors when I issue the ls command and that will cause each command which operates on the variable $dir to fail with a “No such file or directory” error. I always have to remember this and re-write the command with the flag to disable color formatting:

for dir in $(ls --color=never)
do
  echo ${dir}
done

The above script will work every time.

The next option is using find. find is awesome and all powerful. Learn and use find. The most common issue when using find is that you may have to filter out the current and/or parent directories when processing the results. Take this example:

for dir in $(find . -maxdepth 1 -type d)
do
  echo ${dir}
done

This loop will print out the current directory, as well as all other directories in the current working directory. If you are running some sort of processing within this loop, you may end up re-processing everything unless you discard the current working directory (noted by the dot).

This example will not process the current working directory:

for dir in $(find . -maxdepth 1 -type d)
do
  if [ ${dir} == "." ]
  then
    continue
  fi
  echo ${dir}
  while pushd ${dir}
  do
    echo ${dir}
  done
  popd
done

Bash for loops are incredibly useful and easy to work with. Use the above tips and make bash work for you.

• When indicating that you have VMware experience, clearly indicate which features you have experience with. I have interviewed many candidates who claim to be experts on VI3/vSphere and yet have never used clustering or shared storage.
• When asked about rating yourself from 1-5 or 1-10, make sure you understand which side is the proficient side and give an example of what you think is proficient in a particular area.

My methodology is to ask the interviewee to rate themselves and then ask them what that rating means to them. If they rate themselves a 4 out of 5 with general Linux system administration, I then ask them to give me a few examples of what somebody who has a 4/5 rating would be able to do. I then ask them questions based on that assessment. If you can’t win on those terms, you typically can’t win.

It is not my desire to stump somebody in an interview, I would prefer to ask them questions about what they have done in the past and get into a good dialogue about things they are familiar with.  Do your interviewer a favor and be very clear on the resume and during the interview process.

for file in *.html
do
  mv ${file} ${file%%.html}.shtml
done

This uses the ${variable%%match} format which strips the longest match from the end of the variable.