Location of configuration files and parsing order
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The configuration files are parsed in the following order:
1. compiled-in defaults
2. `/usr/local/etc/mtools.conf'
3. `/etc/mtools' This is for backwards compatibility only, and is
only parsed if `mtools.conf' doesn't exist.
4. `~/.mtoolsrc'.
5. `$MTOOLSRC' (file pointed by the `MTOOLSRC' environmental variable)
Options described in the later files override those described in the
earlier files. Drives defined in earlier files persist if they are not
overridden in the later files. For instance, drives A and B may be
defined in `/usr/local/etc/mtools.conf' and drives C and D may be
defined in `~/.mtoolsrc' However, if `~/.mtoolsrc' also defines drive
A, this new description would override the description of drive A in
`/usr/local/etc/mtools.conf' instead of adding to it. If you want to
add a new description to a drive already described in an earlier file,
you need to use either the `+drive' or `drive+' keyword.