You will notice that the parent article mentions "dash." The dash shell is small and fast, but it does not allow any bash/korn language extensions beyond what

You will notice that the parent article mentions "dash." The dash shell is small and fast, but it does not allow any bash/korn language extensions beyond what was recorded in the POSIX.2 standard in the early 1990s. Linux users should care because the Debian/Ubuntu family use dash as the system shell, so this problem is very real as many have learned.