[idea] ignore errors / idempotency

[agardnerIT]

Is it possible to runme run --filename test.md in an idempotent manner?

Imagine the first command was a "set something up". The first time, it would run OK. However for subsequent runs, that first command would output errors that I'd like to ignore (because the hypothetical subsequent commands would still be valid).

[sourishkrout]

There are ways to make the experience better. However, unless you use a devcontainer with all the prerequisites, Runme executing Shell can't know "how valid" the runtime environment is. It's not different from a terminal session.

I can think of several enhancements to improve the status quo. None of which are mutually exclusive.

1. Ignoring errors on the command level

I have used command snippets such as below "successfully" in the past. Essentially, this will turn any non-zero into a zero exit code. It's not ideal because it masks even valid issues. It's a binary choice between erring on false positives or false negatives. Needless to say, this is available now.

$ brew install cmake || true
$ apt install cmake || true

2. Toggleable "set -o pipefail" like behavior with a setting

The idea here would be to define, e.g., on the markdown document level, if errors should bail execution or continue on similarly whether all executed cells are conjoined with OR or AND. Runme does not have this setting yet.

E.g. in the document's frontmatter:
---
pipefail: false
---

3. Define denied / accepted error states per cell

It's not inconceivable to define a list of exit codes that are accepted or denied. For example, 127 usually means a command/executable wasn't found. Similarly, it'd be possible to use substrings of error messages to do the same.

For illustration:

brew install cmake
apt install cmake

What are your thoughts, @agardnerIT?

[agardnerIT]

I think option 2 makes sense. But IMO I'd call it something more obvious like ignore_errors (following Ansible's example)