http://www.purl.org/tcl/home/man/tcl8.4/TclCmd/pkgMkIndex.htm
This is a proc in Tcl that is used to create the package index files, allowing packages to be loaded automatically when package require commands are executed.
example:
pkg_mkIndex . *.tcl *.so
he -verbose option can help point out what properties of your files are giving the [pkg_mkIndex] command trouble.
pyk 2012-11-02 - dgp stated on the irc channel today that pkg_mkIndex is not generally a good idea. It can't possibly solve the problem right for any but the most simple packages, and even for those, typing the index script yourself is just as easy. For automatic maintenance of version numbers, etcl, construction via configure or Make is a better answer. The problem pkg_mkIndex has to solve seems simple in concept, but is in general impossibly difficult, primarily because of the very Tclish design decision to make its packages implicit rather than explicit.
See also pkg_mkIndex pitfalls, pkgMkIndex, A simple package example, package management, How to build good packages, Better Static Package Support for Tcl9