emacs-pager.el

I use emacs shell-mode buffers almost exclusively, which usually works great, except for when something wants to page. Things like less dont really work that great in shell-mode, and in general I would prefer a normal emacs buffer for this anyways.

Unfortunately, emacsclient doesnt really work with piped content, so actually achieving that goal requires Rube Goldberg-ian changes at quite a few points.

How this works

Well-behaving unix programs will use whatever is in $PAGER when showing data that is too big to fit in a terminal screen. So in the shell, we will set $PAGER to a script, but only if emacs is currently running. That script will read the piped data, and write it to a file in /tmp, read it into emacs via emacsclient, and wait until emacs is done with it. In emacs, it will use a small mode for ANSI coloring and keybinds.

Given that sometimes things are paged because they are tens of thousands of lines long (or more), emacs-pager will only color the first 500 lines. That number can be customized with emacs-pager-max-line-coloring

Installation

Make sure you are running an emacs server, so emacsclient will work. This is what I currently use in my init.el

(require 'server)
(unless (server-running-p)
  (server-start))

Make sure that emacsclient is available on your path.

Put emacs-pager (from this repository) somewhere in your path, and make sure it is executable. This will be the thing that accepts the piped data, and sends it to emacs.

In your .bashrc or .zshrc file, put something like this

if [ $INSIDE_EMACS ]; then
    export PAGER="emacs-pipe"
elif [ -x "`which less`" ]; then
    export PAGER="`which less`"
    export LESS="-isR"
    alias lv="less"
else
    export PAGER="/bin/more"
fi

Put emacs-pager.el somewhere on your load-path, and require it. Or, better then that, use something like el-get or quelpa to package it up in a sane manner and make it available for requiring.

Personally, I use (and love) quelpa, here is what I have in my configs

(quelpa '(emacs-pager :repo "mbriggs/emacs-pager" :fetcher github))

Somewhere in your emacs init files, add the following line

(add-to-list 'auto-mode-alist '("\\.emacs-pager$" . emacs-pager-mode))

Usage

M-x shell, and run a command that will invoke a pager (example would be git log --pretty=oneline -n 20 --graph). You should see the output in a new buffer. Press q to close the buffer.

If you go to an external terminal and run the same command, you should see normal pager behaviour.