how to replace Info with Emacs

Question

The info.el library allows us to view manuals not only for ELisp packages, but also for applications that are independent of Emacs.

E.g.,

(info "gcc")

has the same effect as /usr/bin/info:

$ info gcc

---

info, which looks like a simplified & trimmed Emacs, doesn't highlight; whereas Emacs does.

How can I replace info with emacs so that I can get full Emacs feature support?

Answer 1

Here's a way that re-uses your running Emacs instance:

emacsclient --eval '(info "gcc")' --tty --alternate-editor=

(--eval tells the Emacs instance to evaluate a lisp form. --tty ensures that it displays in the current terminal. --alternate-editor= will automatically start Emacs if it isn't already running. See the emacsclient options page for more info.)

In your shell, you'll have to use a function instead of an alias, because emacsclient has no way to properly pass through its arguments as-is to the Elisp form: once --eval is in play, all non-options are interpreted as Elisp.

If you want just the quick and dirty version, this will do:

info()
{
    emacsclient --alternate-editor= --tty --eval "(info \"$1\")"
}

"But what if the argument has characters that are special within lisp strings?" To be robust, we need to escape all \ to \\ and all " to \" - based on the Elisp string syntax and some basic testing, that seems to be enough.

So if you're already using a modern shell like bash/zsh, you can do this:

info()
{
    local escaped_backslashes="${1//\\/\\\\}"
    local escaped="${escaped_backslashes//\"/\\\"}"
    emacsclient --alternate-editor= --tty --eval "(info \"$escaped\")"
}

If you need to be more portable, this should be good enough for most purposes:

info()
{
    emacsclient --alternate-editor= --tty --eval "(info \"$(printf '%s' "$1" | sed 's/\\/\\\\/g; s/\"/\\\"/g')\")"
}

Answer 2

Use emacs -f info-standalone. E.g.,

$ emacs -f info-standalone gcc

---

I prefer alias info='emacs -Q -f info-standalone' in my .bash_profile.