Add command to tail n lines of output

[amancevice]

Is your feature request related to a problem? Please describe.

I'd love a new gum command that allows a user to stream the last n lines of output — very much like how Docker displays steps in the build process.

Describe the solution you'd like

I think the following would be an intuitive interface for users to show the 12 most recent lines of output of brew upgrade:

brew upgrade | gum stream --lines 12 --faint --italic # etc …

Describe alternatives you've considered

I'm not really sure how else to do this on the command line. I suppose a curses library could do it but that's not super convenient

Additional context

N/A

[4Ply]

gum style can do this using the tail command:

brew upgrade | tail -n 10 | gum style --faint --italic

[amancevice]

@4Ply thanks but that doesn't stream the results, it just shows the last 10 lines of the brew upgrade

Docker's build command is a great example of what I'm after. Consider:

cat <<-DOCKERFILE | docker build -
FROM debian
RUN apt-get update && apt-get install -y ruby
DOCKERFILE

When Docker build gets to the RUN statement it streams the output as its running

[ZOrfeas]

I looked around a bit for this, maybe it would fit as added functionality to gum pager? Sort of like how less does it with F since a few versions now.

[ZOrfeas]

I've been thinking of trying to implement this functionality for gum pager over christmas.

1. Are you open to merge requests from general public?
2. is this a good place to start?
   (the idea is to add another function for consuming the stdin as a stream, maybe via a channel)
3. Would you think it's best for this to be a command line argument, a command within the pager interface, both ?

[YoungOak]

Dang, what @ZOrfeas mentioned would be so appreciated! Been testing different ways to try and stream stdout logs from a running api and was sad gum isn't able to handle it.

[amancevice]

For what it's worth, I was able to achieve what I wanted in pure bash: https://github.com/amancevice/spin