posix_shell_getpots [Doku Wiki]

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===== Overview =====

An attempt at summarizing the //right// way to use POSIX-compliant ''getopts''.

A couple links:

  * [[https://pubs.opengroup.org/onlinepubs/9699919799/utilities/getopts.html|https://pubs.opengroup.org/onlinepubs/9699919799/utilities/getopts.html]]
    * [[https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html#tag_12_02|https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html#tag_12_02]]
  * [[https://sookocheff.com/post/bash/parsing-bash-script-arguments-with-shopts/|https://sookocheff.com/post/bash/parsing-bash-script-arguments-with-shopts/]]

===== Starting points =====

First, there has been much blood spilled discussing how to support //optional// arguments using ''getopts'' -- the correct solution is to not do that, as explained in Guideline 7 [[https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html#tag_12_02|here]]. So we won't.

And, second, if the //optstring// handed to getopts starts with a colon, then getopts uses what is called "silent error reporting"; this appears to be the recommended approach, so we'll stick with that. In short, don't do this:

<code>
while getopts ab:c: opt ; do
</code>

Do this (note the leading colon):

<code>
while getopts :ab:c: opt ; do
</code>

Explanation below.

===== Fleshed out example =====

<code>
... coming soon ...
</code>