kacpersh

My friend Kacper told me about an inconvenience that sometimes happened to him - you execute a long running command, then want to do something with the output, but you forgot to redirect it to a file or something, so you have to re-run it all.

The idea is to make the shell/terminal/whatever capture all commands, and make the last command's outputs available to the user easily.

Also, Kacper sounds a bit like "capture". So, it fits.

Screencast

Usage

Download or build `kacpersh` and put it in your `$PATH`

Homebrew:

brew tap irth/irth
brew install irth/irth/kacpersh

You can download precompiled kacpersh from the releases page.

Alternatively, install go and compile it yourself:

go build
sudo mv kacpersh /usr/local/bin

Add it to your `.zshrc`

Currently only ZSH is supported.

echo 'eval "$(kacpersh init zsh)"' >> ~/.zshrc

Run kacpersh and use the `_` alias to retrieve the stdout of the last command.

$ kacpersh
$ # this is now running under kacpersh
$ echo -n 'test\nhello'
test
hello
$ _
test
hello
$ _ | grep hello
hello
$ _
hello

Proof of concept

https://gist.github.com/irth/ffba9da0a9a4f6df54f02fe06605f19c

TODO:

v1

launch users shell (according to SHELL/profile by default) instead of a hardcoded one
communicate over a unix socket, path to which is passed through an env variable (so that u can have more than one shell)
generate config for zsh, so that it can be eval'ed in .zshrc easily
limit the saved buffer size so that it doesn't fill up your ram (for now I hardcoded it to 32MiB)
allow auto-activation through zshrc

v2

in-band signalling - this will allow as to implement buffering for performance, as we don't have to keep perfect synchronisation anymore
see if we can support bash and fish

v3

a version of _ command that doesn't replace the stored output with its own so that you can do something like this:

$ curl example.com/a/slow/api
first line of output
some more output
hello

$ __ | grep some
some more output

$ __ | grep output
first line of output
some more output

v4

capture multiple commands instead of just the last one, decreasing the odds of losing data

sometime along the line...

configuration? (e.g. setting last command buffer limit)

irth/kacpersh