Archives for April 2021

Ubuntu Speedtest

April 18, 2021

Install Speedtest CLI.

sudo apt-get install gnupg1 apt-transport-https dirmngr
export INSTALL_KEY=379CE192D401AB61
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys $INSTALL_KEY
echo "deb https://ookla.bintray.com/debian generic main" | sudo tee  /etc/apt/sources.list.d/speedtest.list
sudo apt-get update
sudo apt-get install speedtest

To run.

speedtest

Result.

$ speedtest
   Speedtest by Ookla
     Server: City of Columbus - Columbus, OH (id = 40410)
        ISP: Spectrum
    Latency:     9.39 ms   (0.63 ms jitter)
   Download:   117.74 Mbps (data used: 60.3 MB)                               
     Upload:    11.81 Mbps (data used: 5.6 MB)                               
Packet Loss:     0.0%
 Result URL: https://www.speedtest.net/result/c/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx (redacted)

Invalid Credentials with gsutil

April 16, 2021

If you’re trying to access GCS (Google Cloud Storage) and you’re getting “Your credentials are invalid. Please run gcloud auth login”, you most likely have a previous key stored in the ~/.boto file. This happens if you previously configured gsutil with your own credentials, then switched over to Google SDK mode. To fix the invalid credentials, edit the ~/.boto file and comment out the auth key.

vim ~/.boto

Comment out.

#gs_oauth2_refresh_token = <token redacted>

Rerun the gsutil ls command. It should work.

Sosreport

April 16, 2021

Install

yum install sos

Run sosreport

sosreport

Case number will be part of exported report located in /var/tmp.

cd /var/tmp

WordPress Critical Error

April 11, 2021

If you get a WordPress “There has been a critical error on your website” error, you probably have an issue with a theme or plugin. The quickest way to troubleshoot is to rename the plugins directory since there’s no way to login. This technically disables all plugins. Rename it back to plugins and enable each plugin one by one.

Disable all plugins.

mv plugins plugins-backup

mv plugins-backup plugins

Enable each plugin one by one and check if the site is broken.

Docker Exec

April 9, 2021

If you want to SSH to a Docker container, use the Docker exec command.

docker exec -it container_name bash

I’m using a Git Bash terminal, so I have to prefix the docker command with winpty.

winpty docker exec -it container_name bash

Result

root@681bbe3f65f1:/var/www/html#

Ctrl-D to exit.

Troubleshoot Nameservers with Dig

April 8, 2021

Here’s how to troubleshoot nameservers with dig.

dig hostname
dig domain.com

To test a specific nameserver.

dig @nameserver hostname
dig @nameserver ip-address

Other options.

dig hostname.domain.com +short
dig hostname.domain.com +noall +answer
dig @nameserver MX domain.com
dig @nameserver AAAA domain.com

Startup Script

April 6, 2021

Here’s how to run a script on bootup on Rhel 7 that’s running systemd.

First create a script. It this case, it will create a file called test.txt.

#!/bin/bash
> /root/test.txt

Make the script executable.

chmod /root/test.sh

Now create a service in /etc/systemd/system/test.service

# vi /etc/systemd/system/test.service
[Unit]
Description=A test service
After=network.target
[Service]
Type=simple
ExecStart=/root/test.sh
TimeoutStartSec=0
[Install]
WantedBy=default.target

Reload systemd.

systemctl daemon-reload

Enable the service.

systemctl enable test.service

Start the service.

systemctl start test.service

Reboot and test.

reboot

Validate if the script ran. Check if the file was created.