Is comma operator defined by POSIX and supported by dash?
According to [Bashism Wiki](https://mywiki.wooledge.org/Bashism):
The comma operator is widely supported by almost everything except dash and yash -- even posh and Busybox. In ksh93 however, it conflicts with the decimal radix in locales where it's used in floating points instead of period
Does it implied that arithmetic comma operator (`,`) isn't defined by
POSIX shell specification? Does dash support it?
An old man doll... just what I always wanted! - Clara