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= How to build Avoid master_sites Redirects  =

 * Audience: Portfile authors 
 * Requires: MacPorts >=2.0

== Introduction ==

In order to be a good 'Net citizen, it is worthwhile to minimize the load on other's servers.  One simple technique is to specify the `master_sites` parameter as specifically as possible so that the other side does not have to supply redirects in order to serve the file we want.  This how-to currently addresses only SourceForge.

== SourceForge ==

Hopefully, the following example, using mediainfo version 0.7.60, will illuminate the process.  The SourceForge home page for mediainfo is [[http://mediainfo.sourceforge.net]].  Initially, just specifying  `'master_sites  sourceforge'` in the portfile under development worked to retrieve the distfile.  The log for `'port fetch'` showed:

{{{
DEBUG: Executing org.macports.fetch (mediainfo)
--->  MediaInfo_CLI_0.7.60_GNU_FromSource.tar.bz2 doesn't seem to exist in /opt/local/var/macports/distfiles/mediainfo
--->  Attempting to fetch MediaInfo_CLI_0.7.60_GNU_FromSource.tar.bz2 from http://iweb.dl.sourceforge.net/mediainfo
}}}

Use 'curl -IL !http://iweb.dl.sourceforge.net/mediainfo/MediaInfo_CLI_0.7.60_GNU_FromSource.tar.bz2' to check for redirects.  In this case the output indicated redirects to a final address of:

{{{
Location: http://voxel.dl.sourceforge.net/project/mediainfo/binary/mediainfo/0.7.60/MediaInfo_CLI_0.7.60_GNU_FromSource.tar.bz2
}}}

To improve the `master_sites` parameter, extract the bit: `project/mediainfo/binary/mediainfo/0.7.60` (and replace "0.7.60"--the version number in this case--with ${version}).  Thus `'master_sites sourceforge:project/mediainfo/binary/mediainfo/${version}'`.

Pat yourself on the back--you're done!



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