Re: [gentoo-user] What is the meaning of "mirror" URI scheme in ebuilds?

[David Haller]

Hello,

On Tue, 27 Mar 2018, Ian Zimmerman wrote:
>Example from app-editors/emacs/emacs-24.5-r5 :
>
>SRC_URI="mirror://gnu/emacs/${P}.tar.xz
>        https://dev.gentoo.org/~ulm/emacs/${P}-patches-4.tar.xz"

It means take one of the list specified in /etc/portage/mirrors/ or
${PORTAGE_DIR}/profiles/thirdpartymirrors

==== man 5 portage =====
       /etc/portage/
[..]
              mirrors
                     Whenever portage encounters a mirror:// style URI it will
                     look up the actual hosts here.  If the mirror set is  not
                     found  here,  it  will  check  the global mirrors file at
                     /usr/portage/profiles/thirdpartymirrors.
====

See also https://wiki.gentoo.org/wiki/GENTOO_MIRRORS

So, using your example, portage looks up the mirror for mirror://gnu
by looking in /etc/portage/mirrors (if it exists) and
/usr/portage/profiles/thirdpartymirrors for a line with the word "gnu"
at the beginning, and then tries the mirrors specified there. I.e.:

# grep '^gnu[[:space:]]' /usr/portage/profiles/thirdpartymirrors 
gnu             http://ftpmirror.gnu.org/ http://ftp.gnu.org/gnu/

So, portage will try http://ftpmirror.gnu.org/emacs/${P}.tar.xz and
http://ftp.gnu.org/gnu/emacs/${P}.tar.xz to retrieve the tarball.

HTH,
-dnh

-- 
"one of the ill effects of Microsoft's software is having to pay for it.
Lusers who pirate it are escaping this particular ill effect and aren't
driven quite as hard toward cheaper, better choices."  -- Mark Wells