[metapost] macro path

[john kitzmiller]

How to update the PATH for MP under linux?

New to linux, I have installed TexLive (2005) under Ubuntu Edgy. So far
all latex and simple MP working fine.

I have put a macro in same location as graph, sarith, etc. and

	input graph

works fine, but

	input myfile

gets 'Can't find file' error.

Seems like I just put the file in right place with winxp/miktex and
could use input at will, but I may have forgotten some other step.

Thanks,

John