Changes

* The program <code>mtxrun</code> requires access to a temporary directory. At least one of the following environment variables must be set to a directory which is writable by the executing process: <code>TEXMFCACHE</code>, <code>TMPDIR</code>, <code>TEMPDIR</code>, <code>TMP</code>, <code>TEMP</code>, <code>HOME</code>, <code>HOMEPATH</code>.

* In addition to the above, the <code>HOME</code> environment variable must be set, but at time of writing there is no particular requirement that its value be a valid or writable location.