Today’s basic crontab info…

Wicked simple issue – took a line from /etc/crontab and put in to the root’s crontab (crontab -u root -e) and it was no longer running.  Getting this error:

/bin/sh: root: command not found

Simple fix – needed to remove the ‘root’ from the line that I’d moved from one file to the other, as the root’s crontab did not need the ‘root’ user mentioned.

A good blog post with some cron/crontab basics: http://rhosted.blogspot.com/2010/04/crontab-error-binsh-root-command-not.html

Last Week’s Links This Week

Here are a few of the things I found useful last week:

  • Forgotten Linux Commands – useful for things like repeating commands, column-izing output, etc.
  • 5 Commands to Check Memory Usage on Linux – more than just the usual top, includes free w/ switches, etc.
  • Commandline Challenge – This is pretty cool!  A good test of your bash chops.  I got stuck waaay too early.
  • Alassian University – if you have been getting inundated with Atlassian ads on WUBR, or actually use Jira and Confluence, this is their corporate training site.  I have taken a little of the official Jira training and so far feel it needs refinement.
  • Xen4 QuickStart – for a project I’m starting this week modeling an older CentOS environment at work.  CentOS host running Xen w/ guests.  Seeing how to migrate them easily over to VMWare.  No need to migrate the hosts, so this should be (hopefully) an easy task for VSphere Standalone Converter.  Still, want to create a test environment first before attempting this with the real thing.
  • A new Linux From Scratch has been released.  I can’t wait to have the time to try out this fun-looking project.
  • EZPrompt – a BASH prompt generator.  Useful if you are too lazy to look this up yourself.
  • Linux Sucks – for the last time.  This YouTube video series has been wicked fun to watch.
  • Playing with rsync deltas – this person’s tips have been very helpful on another modeling project I am working on.

Note: Most of these links from the cron.weekly newsletter.  This is an excellent source of weekly Linux / Open Source News and is worth the time to read weekly.

  • Last one – a good quick read on Gizmodo about Amazon’s outage a couple weeks ago.  Specifically, their AWS service.  If you have a VPS on this service, you are probably painfully aware of this outage.

Making the switch (to Linux)

Over the past year, I have become more and more entangled in the Linux world, becoming a Linux System Administrator as my primary job duty.  Though I have had plenty of Linux experience and exposure, and attend (when I get time) meetings of the Boston Linux Users’ Group (blu.org), I generally approach Linux from a Server angle and only play with it as a desktop, while maintaining a Mac or Windows PC for my primary ‘working’ OS.  This has changed a bit over time and I find myself using Fedora 25 on both my Thinkpad T460s (a post for a different time) and now on my office Dell Precision 3620.  Going to see how long I can keep it up in this windows-centric office.  Desktops and laptops here have been primarily Windows, but we do run some CentOS 6.x and 5.x desktops on the ‘important computers’ side.  Side-note – the Precision 3620 runs CentOS7 and all the apps listed above just fine as well.

Articles and posts such as this one, where people are switching from Mac to Linux OS, are encouraging and the more people use this ecosystem, the more things will be developed for the desktop OS.  It was nice, also, to have someone as famous as Cory Doctrow talk about his switch over to a Linux OS back in January 2016.

Exclude particular packages from updating in Yum on CentOS 6/7

We had an issue here recently where only an older version of OpenConnect would work for a CentOS 6.8 machine.  Installation went fine, but the user was getting yum update messages for this package.  In order to exclude, just make an entry in to your /etc/yum.conf directory.  Instructions can be found right on Redhat’s website: https://access.redhat.com/solutions/10185

 

Linux Certification (Linux+, RHCSA, RHCE) with Linux Academy

In my current full-time role, I am a Linux System Administrator at a nonprofit institution.  I came to this position from a mainly Windows environment, and wanted to refresh and solidify my Linux SysAdmin skillset.  In order to do this, I chose the certification track so that I could re-cover all the basics before learning specialized skills for this particular organization.

I started out with the basic Linux+ certification by reading the Sybex CompTIA Linux+ book as well as starting a subscription to Linux Academy.  This online site includes a ton of video instruction as well as VMs so that you can practice all your skills and tasks without having to have your own local Virtualbox or other server environment.  This VM addition really removes a lot of the pain and overhead while learning and studying for your certs.  I think the cost is ~$20 / month and I highly recommend this service.

Next, I obtained Redhat’s RHCSA certification.  Though my office sent me to the ‘official’ 1-week training, and that was useful, I feel that both practice IRL as well as the Linux Academy stuff would have been enough to pass the exam.

Currently working on RHCE.  Hopefully will get this done over the next couple of months.  Though no certification an substitute for practical experience, and no training takes the place of years of troubleshooting and break / fix experience, I still feel that certification is useful.