The strange install command used by emacs.

The strange install command used by emacs.

[Hongyi Zhao]

On Ubuntu 20.10, when I compile the latest git master version of
emacs, I noticed the following line near to the end of installation
log:

cd "/usr/local/bin" && ln -s "`echo emacs-28.0.50 | sed 's,x,x,'`"
"`echo emacs | sed 's,x,x,'`"

Apparently, it want to do the following job:

ln -s /usr/local/bin/emacs-28.0.50 /usr/local/bin/emacs

The confusing thing is that the pattern feed to sed, i.e., 's,x,x,',
which in fact matches nothing for this case. So why it's useless at
all. Any hints/notes/explanations would be appreciated.

Regards
-- 
Assoc. Prof. Hongyi Zhao <hongyi.zhao@gmail.com>
Theory and Simulation of Materials
Hebei Polytechnic Vocational and Technical University
NO. 552 North Gangtie Road, Xingtai, China

Re: The strange install command used by emacs.

[Philipp Stephani]

Am Fr., 18. Dez. 2020 um 05:58 Uhr schrieb Hongyi Zhao <hongyi.zhao@gmail.com>:
>
> On Ubuntu 20.10, when I compile the latest git master version of
> emacs, I noticed the following line near to the end of installation
> log:
>
> cd "/usr/local/bin" && ln -s "`echo emacs-28.0.50 | sed 's,x,x,'`"
> "`echo emacs | sed 's,x,x,'`"
>
> Apparently, it want to do the following job:
>
> ln -s /usr/local/bin/emacs-28.0.50 /usr/local/bin/emacs
>
> The confusing thing is that the pattern feed to sed, i.e., 's,x,x,',
> which in fact matches nothing for this case. So why it's useless at
> all. Any hints/notes/explanations would be appreciated.

This is likely to support the --program-prefix and --program-suffix
configure options. They can be used to append/prepend a string to the
Emacs binary filename (e.g. to distinguish multiple Emacsen installed
on the same system). By default both are empty, resulting in this
no-op.