Explain how "run" runs whatever it is its value represents

[jcayzac]

:zap: Summary

As far as I could see, the run documentation doesn't explain what the value for that configuration is beyond a "command", nor how Lefthook actually runs it, e.g direct invocation, though sh, through bash, etc.

Value

It's really difficult to understand what kind of command can be used for run, e.g. can pipes | be used? Or && and ||? Can the exit code $? of a command be checked with if? Are scripts even supported at all? What's the behavior of multiple lines (using run: |)? Will execution automatically stop at the first error? etc…

Behavior and configuration changes

Documenting the current behavior.