I’ve been working on a new way to launch and manage processes in Emacs in my personal repo. It’s an alternative to shells. A bit like a notebook. It also partially serves the same need that Prodigy-mode does. The name is evocative of that video game Portal from 2007.
It has a major mode, where M-! is rebound to Portal’s
way of running shell scripts. It inserts a nano-ID for the portal,
e.g. portal_abc123456sdkjfal, as text into the buffer at
the current point. It creates a corresponding directory under
~/.portals/. All stdout and stderr are redirected to files
under
~/.portals/$portalid/{stdout,stderr,command,directory,env}.
The purpose of this is that Emacs can lock up a bit when you run a very long running process, or one that spews output very quickly. Instead of storing it in a buffer or displaying all of it, Portal just writes it all to a file and displays a little preview of it anywhere in the buffer that the portal’s nano-ID is.
The preview is updated every couple seconds, it’s not instant. That design is intentional, so that no process can ever really overwhelm Emacs. It’s an extremely aggressive design. Even the line length in the preview is limited to 80 columns.
Another motivation is simply UX-based, which is that I run a lot of commands at work that spit out a bunch of useless output. Like Terraform, Cabal, GHC, etc. Most of the output is not of interest, but occasionally, one does want to read the output.
Example, below:
portal_M2FjMjMyZWIxZjI4MTNmN
# (0) ls
# package.yaml
# readme.md
# scripts
# stack.yaml
# stack.yaml.lock
portal_ZmZhZThiMmFiNzQ1Y2E3N
# (run) stack build
# Preparing to download ghc-tinfo6-libc6-pre232-9.4.8 ...
# ghc-tinfo6-libc6-pre232-9.4.8: download has begun
# ghc-tinfo6-libc6-pre232-9.4.8: 256.00 KiB / 178.01 MiB ( 0.14%) downloaded..
# ghc-tinfo6-libc6-pre232-9.4.8: 432.00 KiB / 178.01 MiB ( 0.24%) downloaded..
# ghc-tinfo6-libc6-pre232-9.4.8: 736.00 KiB / 178.01 MiB ( 0.40%) downloaded..The (0) indicates a successful exit. The command, stdout and stderr have different colours. In the major mode, you put your cursor over them and hit RET and it’ll pop open the file for you.
The other reason for storing all of this is that one can restart Emacs and re-open a file containing portals and see what was ran, and re-launch them if desired, with the same arguments, directory, etc.
I often use M-x portal-edit to tweak a command line,
which prompts in the mini-buffer with the existing text to edit. After
hitting RET, it restarts the portal for you.
M-x portal-rerun does what you’d expect.
All newly ran portals get a new nano-ID, so you can always go back and find the outputs of a previously ran portal.
Emacs handles all the stdout and stderr, so it could in theory be possible to pipe from one portal to another. One could even attach and detach portals to/from one another, or edit arguments and restart, while some of the processes are still running. But I haven’t explored this because it’s more of a side-effect of my design than an intentional part of it.
It also works perfectly with envrc mode, which is how Emacs integrates with direnv.
C-c C-c on a portal will interrupt the process, as
expected.
I’ve been using this for a few weeks and frankly I’m surprised how well it works and fits my workflow. At work I have a foo.portals buffer which has 30 portals in it. Of those, 3 are presently running, the rest are things I can scroll through and re-run when I feel like it. I save the file, so I can always restart Emacs and lose nothing.
I’m not interested in maintaining it as a “package.” But in the spirit of Emacs, I am interested in sharing the code, so that others can rip, riff and remix! Hope someone found this fun!