In this example dash will repeatedly append 'attr=foo' to the list of
parameters in an infinite loop:
#!/bin/dash -x
while getopts :a: arg -a foo -a bar; do
case $arg in
a) set -- "$@" attr="$OPTARG"
esac
done
shift "$((OPTIND - 1))"
Instead I expected this to result in parameter list containing
'attr=foo' and 'attr=bar'.
This works in all shells I have been able to test with the exception of
busybox sh:
* sh (bash)
* bash (All versions from 1.14 through 5.1.4)
* mksh (MIRBSD KSH R59 2020/05/16)
* ksh (93u+)
* zsh (5.8)
* zsh --emulate sh
* heirloom-sh (bourne)
The only workaround I've found is to explicitly use `shift 2` in the a)
case and obviate the final shift using OPTIND. This will unfortunately
break every other shell.
