How can I put together a small bare bones "Emacs for scripting" package?

How can I put together a small bare bones "Emacs for scripting" package?

[Mathias Dahl]

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Hi,

I am writing a lot of tools for my own use at work in Emacs. Sometimes I
like to share these tools with friends who are not using Emacs. I have
tried this a few times and I have ended up zipping my whole Emacs file
structure together with some scripts to start Emacs and do the stuff for
them.

This approach kind of works, but today I got thinking: how little could I
actually copy from my Emacs installation to have basic scripting working?
And with basic scripting I mean basic file handling (creating, checking
for, deleting), buffer handling and basic text manipulation stuff.

Obviously I would need emacs.exe. On my Windows installation it's around 9
MB. A bit on the big side for a scripting engine, still not bad by today's
standards.

But what would I need more, for Emacs to even start? If I knew the bare
minimum of what is needed to start, I think I would be able to add in any
additional features just by copying those Elisp files.

Any thoughts, comments or pointers to further reading?

Thanks!

/Mathias

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Re: How can I put together a small bare bones "Emacs for scripting" package?

[Eli Zaretskii]

> From: Mathias Dahl <mathias.dahl@gmail.com>
> Date: Fri, 24 Jan 2020 16:34:08 +0100
> 
> Obviously I would need emacs.exe. On my Windows installation it's around 9 MB. A bit on the big side for a
> scripting engine, still not bad by today's standards.
> 
> But what would I need more, for Emacs to even start? If I knew the bare minimum of what is needed to start, I
> think I would be able to add in any additional features just by copying those Elisp files.

Start with emacs.exe alone, and then add *.elc files according to
error messages you get.  You will need lisp/term/w32-win.el at least,
but other than that, I don't know.

Re: How can I put together a small bare bones "Emacs for scripting" package?

[Eli Zaretskii]

> Date: Fri, 24 Jan 2020 17:49:11 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: emacs-devel@gnu.org
> 
> Start with emacs.exe alone, and then add *.elc files according to
> error messages you get.  You will need lisp/term/w32-win.el at least,
> but other than that, I don't know.

I see you'd also need simple.elc (because we look for it at startup),
and with Emacs before 27 also mule-util.elc.  Emacs will probably
complain about a missing libexec directory, so create it.

Re: How can I put together a small bare bones "Emacs for scripting" package?

[Mathias Dahl]

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>
> > Start with emacs.exe alone, and then add *.elc files according to
> > error messages you get.  You will need lisp/term/w32-win.el at least,
> > but other than that, I don't know.
>
> I see you'd also need simple.elc (because we look for it at startup),
> and with Emacs before 27 also mule-util.elc.  Emacs will probably
> complain about a missing libexec directory, so create it.
>

Thanks!

Got it to work.

Here seems to be the bare minimum structure needed for Emacs 26.3 on
Windows 10:

./bin
./bin/emacs.exe
./libexec
./libexec/emacs
./libexec/emacs/26.3
./libexec/emacs/26.3/x86_64-w64-mingw32
./share
./share/emacs
./share/emacs/26.3
./share/emacs/26.3/etc
./share/emacs/26.3/etc/charsets
./share/emacs/26.3/etc/charsets/8859-10.map
... a lot of map files goes here ..
./share/emacs/26.3/lisp
./share/emacs/26.3/lisp/simple.el
./share/emacs/26.3/lisp/term
./share/emacs/26.3/lisp/term/w32-win.el

I could then successfully do this (from cmd.exe, a similar command also
worked from Git Bash)

  C:\...> bin\emacs.exe --batch -Q --eval "(princ """This is cool!""")"
  This is cool!
  C:\...>

I might write up something more detailed on EmacsWiki later. It took a bit
of trial and error to get it to work and the error messages are only partly
helpful (they mention looking in c:\emacs, a folder that does not exist,
and which is not needed).

One thing that I noticed is the HUGE difference in size of the exe file
between Emacs 24 and later versions. I listed the sizes of the folder when
I keep my different Emacs versions:

8.8M    ./emacs-24.5-official/bin/emacs.exe
91M     ./emacs-25.1-2-x86_64-w64-mingw32_2016_11_16/bin/emacs.exe
119M    ./emacs-26.1-x86_64/bin/emacs.exe
120M    ./emacs-26.2-x86_64/bin/emacs.exe
130M    ./emacs-26.3-x86_64/bin/emacs.exe
16M     ./emacs-bin-w64-24.4/emacs/bin/emacs.exe
121M    ./emax64-bin-20180529/emax64/bin/emacs.exe
119M    ./old/emacs-26.1/bin/emacs.exe

Now, I can probably use an old version for the mentioned scenarios (using
Emacs as a kind of scripting engine), but I am curious about the jump in
sizes. I assume that later versions include something that was earlier
"outside", in separate files, is that right? If I wanted to, could I reduce
the size by building Emacs myself? Is this in some way related to "dumping
Emacs"?

/Mathias

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Re: How can I put together a small bare bones "Emacs for scripting" package?

[Eli Zaretskii]

> From: Mathias Dahl <mathias.dahl@gmail.com>
> Date: Fri, 24 Jan 2020 22:37:14 +0100
> Cc: emacs-devel@gnu.org
> 
> One thing that I noticed is the HUGE difference in size of the exe file between Emacs 24 and later versions. I
> listed the sizes of the folder when I keep my different Emacs versions:
> 
> 8.8M    ./emacs-24.5-official/bin/emacs.exe
> 91M     ./emacs-25.1-2-x86_64-w64-mingw32_2016_11_16/bin/emacs.exe
> 119M    ./emacs-26.1-x86_64/bin/emacs.exe
> 120M    ./emacs-26.2-x86_64/bin/emacs.exe
> 130M    ./emacs-26.3-x86_64/bin/emacs.exe
> 16M     ./emacs-bin-w64-24.4/emacs/bin/emacs.exe
> 121M    ./emax64-bin-20180529/emax64/bin/emacs.exe
> 119M    ./old/emacs-26.1/bin/emacs.exe

The small ones are stripped, the large ones are with debug info.  If
you have the 'strip' command (from Binutils) installed, you can strip
the large ones as well.

Re: How can I put together a small bare bones "Emacs for scripting" package?

[Mathias Dahl]

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>
> > One thing that I noticed is the HUGE difference in size of the exe file
> between Emacs 24 and later versions. I
> > listed the sizes of the folder when I keep my different Emacs versions:
> >
> > 8.8M    ./emacs-24.5-official/bin/emacs.exe
> > 91M     ./emacs-25.1-2-x86_64-w64-mingw32_2016_11_16/bin/emacs.exe
> > 119M    ./emacs-26.1-x86_64/bin/emacs.exe
> > 120M    ./emacs-26.2-x86_64/bin/emacs.exe
> > 130M    ./emacs-26.3-x86_64/bin/emacs.exe
> > 16M     ./emacs-bin-w64-24.4/emacs/bin/emacs.exe
> > 121M    ./emax64-bin-20180529/emax64/bin/emacs.exe
> > 119M    ./old/emacs-26.1/bin/emacs.exe
>
> The small ones are stripped, the large ones are with debug info.  If
> you have the 'strip' command (from Binutils) installed, you can strip
> the large ones as well.
>

Ah, makes sense.

I tried three different versions of MingW and binutils/strip until I found
one that did not fail :)

Now I have an emacs.exe (emacs-26.3-x86_64-no-deps, from the official Gnu
download location) that is 30 MB in size instead of 132 MB :) And, it still
seems
to work.

Thanks a lot!

/Mathias

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Re: How can I put together a small bare bones "Emacs for scripting" package?

[Mathias Dahl]

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> Now I have an emacs.exe (emacs-26.3-x86_64-no-deps, from the official Gnu
> download location) that is 30 MB in size instead of 132 MB :) And, it still
> seems
> to work.
>

For the benefit of those who have no means to strip their own exe, I
uploaded my 26.3 version with a small explanation, here:

https://github.com/mathiasdahl/misc-emacs-stuff

/Mathias

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