Author Archives: Rudy Amid

TMUX: A Command Line Must!

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When I started with Unix, it was during my college days on a VT-100 terminal, with text command lines. There was even an online chat window using text (remember “talk”?). When a GUI was introduced using X Windows on Sun Microsystem Solaris machines, the experience was so different and it was considered to improve productivity because we get to multitask. However, old habits die hard, so even with a GUI, I would have dedicated X-Term windows for command line stuff. I would run “screen” (aka “Gnu Screen”) to have multiple (and switchable) windows within X-Term.

The advantages of using screen are:

  1. When my SSH connection is broken, the command line sessions are still working. Useful when running shell scripts that take a long time to complete.
  2. Having a shell with command line history, I could review the previous executions, in case I forgot to document something.
  3. Instead of using the mouse to click on a different window, I use the keyboard shortcut Ctrl-A and the number keys, to switch between screens. Way quicker.

With the introduction of Red Hat Enterprise Linux 8, I was introduced (read: forced) to use a new screen replacement called TMUX. Apparently, it’s not a new util but it’s way more powerful – and useful. After using it for a while, I saw these advantages:

  1. Having a vendor managed Firewall, I didn’t have a choice for connection keep-alives. My SSH connections will drop after inactivity. With TMUX, there’s a clock display that forces the connection to send data once a minute. Thus keeping the connection alive – indefinitely. No more dropped connections and reconnecting effort.
  2. Being able to run screen within TMUX window is pretty nifty. I have another layer of switchable window, which is really handy when I have multiple servers representing the different layers for a site (ie. web, JBOSS, database, etc.) This is possible because TMUX’s key bindings for switching window is configurable and by default it’s different than screen’s.
  3. TMUX has window panes, for dashboard like monitoring. Plus, it looks awesome!
My tmux screen with split panes (For demo only. I usually like to see one window at a time)

Most of the Red Hat Enterprise Linux I’m working with is version 6.x, TMUX is not included as part of RHN repository. Thus, I had to build it from source. These are the steps to do it:

  1. Download, compile, and install the latest libevent and ncurses.
  2. Download TMUX and compile using the following configure flags (note, I installed on local home directory):
    CFLAGS="-I$HOME/local/include -I$HOME/local/include/ncurses" LDFLAGS="-L$HOME/local/lib -L$HOME/local/include/ncurses -L$HOME/local/include" CPPFLAGS="-I$HOME/local/include -I$HOME/local/include/ncurses"

If there’s a doubt that command line is important to a sysadmin’s daily work, Microsoft Developers are proud to present an expanded version of Windows OS command prompt. The video below has the full highlights and it looks great!

Windows Terminal: Building a better command line experience for developers

There’s even a trailer that rivals an iPhone launch commercial!

The new Windows Terminal: Trailer

I’m excited that Operating System vendors are now providing more robust terminal tools, making command line a much better experience for all of IT folks!

Re-Index With Elasticsearch

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Elasticsearch Logo

When dealing with indices, it’s inevitable there will be a need to change the mapped fields. For example, in a firewall log, due to default mappings, a field like “RepeatCount” was stored as text instead of integer. To fix this, first write an ingest pipeline (using Kibana) to convert the field from text to integer:

PUT _ingest/pipeline/string-to-long
{
  "description": "convert RepeatCount field from string into long",
    "processors": [      
      {
        "convert": {
          "field": "RepeatCount",
          "type": "long",
          "ignore_missing": true
        }
      }
    ]
}

Next, run the POST command reindex the old index into the new one, while running the pipeline for conversion:

POST _reindex 
{ 
   "source": { 
      "index": "fwlogs-2019.02.01" 
   }, 
   "dest": { 
      "index": "fwlogs-2019.02.01-v2", 
      "pipeline": "string-to-long"
   } 
}

If there are multiple indices, it’s recommended to use a shell script to deal with the individual index systematically, such as “fwlogs-2019.02.01”, “fwlogs-2019.02.02”, etc.

#!/bin/sh
# The list of index names in rlist.txt file
LIST=`cat rlist.txt`
for index in $LIST; do
  curl -HContent-Type:application/json --user elastic:password -XPOST https://mysearch.domain.net:9200/_reindex?pretty -d'{
    "source": {
      "index": "'$index'"
    },
    "dest": {
      "index": "'$index'-v2",
      "pipeline": "string-to-long"
    }
  }'
done

Finally, clean up the old indices by deleting them. It’s a temptation to use Kibana to DELETE fwlogs-2019.02*, but beware the new indices have the suffix “-v2” and it will be deleted if the wildcard argument is used. Instead use the shell script to delete based on the names specifically listed in the txt file.

#!/bin/sh
# The list of index names in rlist.txt file
LIST=`cat rlist.txt`
for index in $LIST; do
  curl --user elastic:password -XDELETE "https://mysearch.domain.net:9200/$index"
done

Hype Cycle 2018 For Web Applications

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By Jeremykemp at English Wikipedia, CC BY-SA 3.0

Technology changes quickly. This is especially true in web development. With companies such as Google, Facebook, Amazon, or Netflix leading the way, there will always be the “next best thing” every IT professional has to pay attention to. Depending on the size and budget, not all companies can invest in the latest trend of technology. The question always asked: “What can we invest in?” As a guideline, annually Gartner publishes their infamous Hype Cycle, that charts the popularity (or decline) of technology. For those who are on the cutting edge will try to follow anything towards the “Peak of Inflated Expectations”, where the technology is hot. However, the most interesting set are the ones sliding into the “Trough of Disillusionment”. In 2018, those web applications were:

  • Point-of-Decision HTAP
  • Cloud-Native Application Architecture
  • Reactive Programming
  • Microservices
  • Mesh App and Service Architecture
  • Public Web APIs
  • Miniservices

Enterprise has already started to invest in those declining trendy ideas.  However, in order to get to full adoption, IT Professionals have to familiarize with (and embrace) the new technology. It’ll be a difficult journey, but may be worth the investment. At this point, a great deal of material will be available since the concept has been around for a few years already. This is known as the “Slope of Enlightenment”. In order to get started, here are some suggestions on which presentation to listen to:

After listening to the presentations, one can determine the trend and make decisions on where/how to go to get Enterprise environments to the next level. It’ll take more time to get to the “Plateau of Productivity” where value can be realized by streamlining their execution for the long term production use.

Enterprise sure has plenty of work to do!