To construct its built-in @getconf@ command, the ksh93 configuration system extracts information from the system getconf binary and from several headers. Unfortunately, the script that does this expects GNU sed and in particular tries to use sed to substitute newlines for spaces. This does not work and as a result several parameters are not exposed in the built-in. This was discovered when richlowe generated the ksh93 feature files on a system which had GNU sed earlier in the path than /usr/bin; there's a secondary problem that the user's path can affect the feature generation. Note that this is not part of a standard build, it's a manual process to re-generate re-generated the feature files that ksh93 needs to build.