There is ::group “command” which allows to hide boring parts of scripts. Can’t remember where i found this; it’s not in docs, so either it was used by someone else in their workflow, or inside ‘actions/toolkit’ repo.

Anyway.

- run: |
       echo Important stuff
       echo ::group::Boring stuff
       echo very
       echo boring
       echo stuff
       echo ::endgroup::
       echo Exciting stuff

will become

Important stuff
▶ Boring stuff
Exciting stuff

when checking workflow run under Actions tab, with “Boring stuff” clickable to expand group.

There are two minor issues with ::group i know of:

• Colorizing warnings/errors breaks ::group 

• Commands writing to error stream might ‘escape’ grouping (see last answer by thboop)

Not sure if first one is still valid, but second one i still can see in recent runs; easy to avoid.

- run: |
         echo ::group::Stuff
         ./name 2>&1
         echo ::endgroup::
  shell: bash