Uly.me

cloud engineer

change

Change WordPress URL

There are multiple ways to change URL in WordPress.

Here’s one via wp-config.php.

define( 'WP_HOME', 'http://example.com' );
define( 'WP_SITEURL', 'http://example.com' );

If you have a redirect in Apache, comment it out.

#Redirect permanent / https://yourdomain.com/

This is by far the easiest way to change URL in WordPress.

Change MySQL User Password

This is a very simple command to run. Login to MySQL first and run the following the command line.

ALTER USER username IDENTIFIED BY 'password';

Flush privileges for changes to take effect.

flush privileges;

Change Default Editor

Ubuntu and Linux Mint use nano as their default editor. You’ll see it if you try to edit crontab or visudo. Now, there’s nothing wrong with nano, but I prefer using vim instead. Here’s how to change the default editor.

sudo update-alternatives --config editor

You’ll be prompted to change the default editor.

There are 4 choices for the alternative editor (providing /usr/bin/editor).
 
  Selection    Path                Priority   Status
------------------------------------------------------------
  0            /bin/nano            40        auto mode
  1            /bin/ed             -100       manual mode
  2            /bin/nano            40        manual mode
* 3            /usr/bin/vim.basic   30        manual mode
  4            /usr/bin/vim.tiny    15        manual mode
 
Press <enter> to keep the current choice[*], or type selection number:

Type 3 to choose vim basic.

GCP Change Instance Type

Here’s how to change instance types via the command line

# Set Project
gcloud config set project your-project-id
 
# Change instance type to 2 CPU 20GB memory.
gcloud compute instances set-machine-type your-server-name \
--zone us-east1-a \
--machine-type n2-custom-2-20480
 
# Change instance type to original settings.
gcloud compute instances set-machine-type your-server-name \
--zone us-east1-a \
--machine-type n2-custom-2-15360

Route 53 Policy to Change Records

Here’s the IAM policy you’ll need to change Route 53 DNS records. Substitute with your own hosted zone id. 

{
   "Statement":[{
      "Effect":"Allow",
      "Action":["route53:ChangeResourceRecordSets"],
      "Resource":"arn:aws:route53:::hostedzone/*HOSTEDZONEID*"
      }
   ],
   "Statement":[{
      "Effect":"Allow",
      "Action":["route53:GetChange"],
      "Resource":"arn:aws:route53:::change/*"
      }
   ]
}

Add to policy to a user.

Change DNS Records in Route 53 via CLI

How to change DNS records in Route 53 via AWS CLI.

  • Assuming AWS CLI is already configured
  • Uses Route53 change-resource-record-sets to update DNS records
  • Substitute with your own hosted-zone-id
  • Uses JSON files containing record sets
  • See JSON file examples below 
cd /path/to/scripts/
# the command to switch to the elb
aws route53 change-resource-record-sets --hosted-zone-id xxxxxxxxxxxxxx --change-batch file://elb.json
# the command to switch to standard site
aws route53 change-resource-record-sets --hosted-zone-id xxxxxxxxxxxxxx --change-batch file://live.json

elb.json = points to AWS ELB (elastic load balancer)

{
   "Comment": "back to elb",
   "Changes": [
      {
         "Action": "UPSERT",
         "ResourceRecordSet": {
            "Name": "yourdomain.com",
            "Type": "A",
            "AliasTarget": {
               "HostedZoneId": "xxxxxxxxxxxxxx",
               "EvaluateTargetHealth": false,
               "DNSName": "xxxxxxxxxxxxx.us-east-1.elb.amazonaws.com."
            }
         }
      }
   ]
}

live.json = points to your standard site. Value is your IP Address.

{
   "Comment": "back to live",
   "Changes": [
      {
         "Action": "UPSERT",
         "ResourceRecordSet": {
            "Name": "yourdomain.com",
            "Type": "A",
            "TTL": 60,
            "ResourceRecords": [
               {
                  "Value": "xxx.xxx.xxx.xxx"
               }
            ]
         }
      }
   ]
}