Doing a little Bash scripting:

[Reading on exit codes](http://www.rdio.com/artist/Carolina_Chocolate_Drops/album/Dona_Got_a_Ramblin%27_mind/).

[And](http://www.tldp.org/LDP/abs/html/exitcodes.html#EXITCODESREF):

> There has been an attempt to systematize exit status numbers (see
> /usr/include/sysexits.h), but this is intended for C and C++ programmers. A
> similar standard for scripting might be appropriate. The author of this
> document proposes restricting user-defined exit codes to the range 64 - 113
> (in addition to 0, for success), to conform with the C/C++ standard. This
> would allot 50 valid codes, and make troubleshooting scripts more
> straightforward. [2] All user-defined exit codes in the accompanying examples
> to this document conform to this standard, except where overriding
> circumstances exist, as in Example 9-2.

For the moment, a reasonable pattern to follow seems like:

1. If it's just some general error, `exit 1`
2. If I want to specify meaningful codes, use something 64-113.


* [Debian New Maintainers' Guide](https://www.debian.org/doc/manuals/maint-guide/)