doc(README): Make shell snippet copy&paste safe #336
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Many bash/shell snippets in the README use an environment variable `YOUR_CONTAINER_REGISTRY`, which is used as `$YOUR_CONTAINER_REGISTRY`. However, that has the downside that if users copy & paste the snippet and accidentally press enter or use a shell that doesn't allow multi- line pasting (and executes it immediately), then the variable will be replaced by an empty string, because it wasn't set before. It's good practice to make those snippets copy&paste-safe. We can achieve that by adding `:?` to the variable, which emits an error if the variable is unset or null. See https://devhints.io/bash for a bash cheat sheet. Example: ```sh docker push ${YOUR_CONTAINER_REGISTRY:?}/bookshop-srv ``` On ZSH: ``` zsh: YOUR_CONTAINER_REGISTRY: parameter not set ``` On Bash: ``` bash: YOUR_CONTAINER_REGISTRY: parameter null or not set ```
davidhunglam
approved these changes
Jun 26, 2024
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Actually, most people replace the whole string in the copied command. But in cases where an actual env variable is used, this is quite nice. |
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@davidhunglam The issue is that some shells auto-executed a pasted snippet if it ends with a trailing newline. That has happened a few times in the past for me, when I didn't setup my shell properly. 😄 This is just a safe-guard. I'd also expect users to replace the variable altogether and not set it in their shell. |
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Thanks for reviewing my change, David! 😄 |
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Many bash/shell snippets in the README use an environment variable
YOUR_CONTAINER_REGISTRY, which is used as$YOUR_CONTAINER_REGISTRY.However, that has the downside that if users copy & paste the snippet and accidentally press enter or use a shell that doesn't allow multi- line pasting (and executes it immediately), then the variable will be replaced by an empty string, because it wasn't set before.
It's good practice to make those snippets copy&paste-safe. We can achieve that by adding
:?to the variable, which emits an error if the variable is unset or null.See https://devhints.io/bash for a bash cheat sheet.
Example:
docker push ${YOUR_CONTAINER_REGISTRY:?}/bookshop-srvOn ZSH:
On Bash: