Command-Line on Bill Glover

How to upgrade Ubuntu on Digital Ocean

hello@bill.dev (Bill) — Fri, 02 Sep 2022 21:32:13 +0100

How to upgrade Ubuntu on Digital Ocean

When canonical release a new version of Ubuntu, you are prompted to run this command to upgrade.

do-release-upgrade

Running this command on a Digital Ocean droplet will give you the following warning.

“Some third party entries in your sources.list were disabled. You can re-enable them after the upgrade with the ‘software-properties’ tool or your package manager.”

You can continue the upgrade but it will fail and roll-back to the previous version. The error you are given includes the following phrase.

Update Trivy Database in Harbor

hello@bill.dev (Bill) — Thu, 19 May 2022 14:56:00 +0000

I recently deployed Harbor and Trivy with automatic updating disabled. I hadn’t realise that this would prevent images from being scanned at all and so needed to trigger a manual update. This note describes how to manually trigger an update to the Trviy database in Harbor deployed on top of VMware Tanzu Kubernetes Grid.

Demo

Instructions

Switch context to the cluster where you have deployed Harbor.

Writing multi-line strings into a text file in bash script

hello@bill.dev (Bill) — Thu, 24 Mar 2022 22:36:19 +0000

Problem: I wanted to use a shell script to write multi-line strings into a text file. I didn’t want parameters or commands to be substituted in the text being written.

Solution: You need to quote the limit string when specifying your here-document.

References

My fist discovery was that the pattern for doing this in a shell script was called a “Here Document”. I don’t think I have ever looked up the bash manual before. But this is where I found the solution.

Replace Environment Variables in a File

hello@bill.dev (Bill) — Mon, 21 Mar 2022 20:17:59 +0000

Every now and again you stumble across a command that solves a problem you didn’t realise you had. Recently, I discovered envsubst.

“Substitutes the values of environment variables.”

I’ve found myself substituting environment variables in configuration files increasingly often (see: Kubernetes). On more than one occasion I’ve tied myself in knots trying to do this with scripts. It turns out that envsubst does most of what I need.

Take the following file, example.yaml: