Frequently Asked Questions
What happens when the repository is offline?
Scripts won’t work. There are exceptions e.g., if the cache holds all required scripts, but in many cases the script just will not run. To avoid such a dependency on a working server you can compile your script into a static script with our module compiler.
What is the difference between module.sh and mdl.sh?
Those are both domains of this project. The website is hosted on module.sh and the code repository on mdl.sh (which is module.sh with the vowels removed). We thought that it would be nice to have a short domain like mdl.sh to be used in the code.
Why do you use cksum and not something more secure like sha256sum?
For POSIX compliance. To our knowledge cksum is part of POSIX and should be available on all POSIX compliant operating sytems. Nevertheless, for your own scripts you can choose something stronger. Just take a quick look at how the validation happens. For example:
module "helloWorld" "https://mdl.sh/misc/hello-world/hello-world-1.0.1.sh" "sha256sum-b92a2908dfa6fde76550702e375939688c53b46e96cae882781e067ba8549d80"
Why should I not want to use module.sh at all?
Foremost, it makes your scripts slower. There are different factors here:
- When you use the dynamic version, the time to fetch the module obviously adds to the runtime.
- Modules are being wrapped in sub-shells, in order to give them a separate scope. Depending on your coding style and use-case, this can add quite much run time.
If you use the compiler, your scripts will also increase in size. Not just because of the module wrapping code, but also because the same module might be included multiple times (if multiple modules depend on it). This is because we favor a simple and robust architecture over static script size.
After all, we consider these downsides acceptable since shell coding is not about speed, but about composability. So if performance is an issue for you, you might want to take a look a different programming language anyway (like C, Go, Rust, et al.)
Are there any tools to help me write POSIX compliant modules?
Shellcheck is a good start and there is a nice list with commands supported by POSIX complient operating system.
