[dev-context] Help regarding Kpsewhich and mtxrun

Please correct me if i am wrong. If kpsewhich is not used and replaced by mtxrun why is it included in context minimals?? Doubt: Inside texexec file i find this line: mtxrun --usekpse --execute texexec "$@" Suppose say i type the following command. texexec --pdf sample.tex It will somehow call mtxrun which in turn will invoke 'texmfstart.rb' i guess. The above command somehow invokes 'pdftex' which processes sample.tex file. But pdftex is a binary how does it come to know about location of fonts and all other information unless there is some interface that is hard coded???