Ruby on Rails json LoadError

Problem:
Running Ruby on Rails 'bin/rails s' and you get an error

in require: cannot load such file -- json (LoadError)


Solution:
Edit the Gemfile and add

gem 'json'

Installing Ruby on Rails on AWS Linux

To install Ruby on Rails on the AWS Linux VM, you need to install some prerequisites first.

sudo su -
yum install -y ruby24
alternatives --set ruby /usr/bin/ruby2.4
yum install -y ruby24-devel rubygems ruby24-devel gcc zlib-devel patch sqlite-devel
curl -sL https://rpm.nodesource.com/setup | bash -
yum install -y nodejs

gem install rails
rails --version

Add hard disk to VMware CentOS 7 VM

There are two easy steps to add a hard disk for a a VMware CentOS 7 VM

1.  Assign a new hard disk in VMware vSphere
2.  Configure the new hard disk in CentOS

See the full picture tutorial at
https://dev.to/juttayaya/add-hard-disk-to-vmware-centos-7-vm-22m8

Get the original username of sudo

For auditing and logging purposes, I needed to get the original Unix login username and not the sudo account name.

The Unix command to get the original login username is

logname 

With the logname command, the operator can su and sudo to various accounts and it will still display the original login.

To try it on a Unix prompt

sudo su - oracle
echo My sudo id is $(whoami) and my login id is $(logname)

Output:
My sudo id is oracle and my login id is juttayaya

---

Reference:https://stackoverflow.com/questions/4598001/how-do-you-find-the-original-user-through-multiple-sudo-and-su-commands

MacBook Pro 2012 broken GPU fix

I have a 17" 2011 MacBook Pro that suffers from the notorious GPU video failure (https://www.bit-tech.net/news/tech/laptops/apple-admits-gpu-design-flaw/1/)

Here is the work-around to turn off the GPU. Credit to PeytonPlaysMc

1. Boot into Recovery Mode
   For High Sierra 10.13.4 or earlier:
   Hold Command+R+S keyboard buttons while pressing the power button
   
   For High Sierra 10.13.5 or later:
   Command+R+S (Recovery mode Single-user) no longer works.
   https://apple.stackexchange.com/questions/332587/single-user-recovery-mode-on-high-sierra-10-13-6
   
   To get to Recovery Mode,
   * Hold Command+S and press the power button
   * On prompt, type command
   

   nvram fa4ce28d-b62f-4c99-9cc3-6815686e30f9:gpu-power-prefs=%01%00%00%00

   reboot
   * Hold Command+R to enter Recovery Mode GUI
   * Click on "Utilities" on the top menu bar and pick "Terminal"
   * Goto Step 2 below
   
2.  Disable System Integrity Protection (SIP)
    Type on the command prompt
   csrutil disable
3. Reboot MacBook Pro into Single User mode
   Type on the command prompt
   reboot
   Then hold Command+S keyboard buttons
4. Hard disk check
   Type on the command prompt
   /sbin/fsck -fy
5. Mount root file system in read-write mode
   Type on the command prompt
   /sbin/mount -uw /
6. Make a directory to save the AMD drivers
   Type on the command prompt
   mkdir /AMD_save
7. Move AMD drivers to the save directory
   Type on the command prompt
   mv /System/Library/Extensions/AMD* /AMD_save
8. Delete AMD driver cache
   Type on the command prompt
   rm -rf /System/Library/Caches/com.apple.kext.caches/
9. Create AMD drive cache directory
   Type on the command prompt
   mkdir /System/Library/Caches/com.apple.kext.caches/
10. Force refresh of drive cache and reboot
    Type on the command prompt
    touch /System/Library/Extensions/
    

    nvram fa4ce28d-b62f-4c99-9cc3-6815686e30f9:gpu-power-prefs=%01%00%00%00

    reboot
11. Boot into Recovery ModeFor High Sierra 10.13.4 or earlier:
    Hold Command+R+S keyboard buttons
    
    For High Sierra 10.13.5 or later:
    See step 1 above
12. Enable System Integrity Protection (SIP)Type on the command prompt
    csrutil enable
13. Reboot MacBook Pro to normal mode.Type on the command prompt
    reboot
14. Launch Terminal in UI and type
    

    sudo nvram fa4ce28d-b62f-4c99-9cc3-6815686e30f9:gpu-power-prefs=%01%00%00%00

15. Restart MacBook Pro one final time