The Almquist shell first appeared in 1989, which predates the POSIX.2 standard shell from 1992. The new POSIX features were likely retrofitted onto the code. h

The Almquist shell first appeared in 1989, which predates the POSIX.2 standard shell from 1992. The new POSIX features were likely retrofitted onto the code. https://en.wikipedia.org/wiki/Almquist_shell https://en.wikipedia.org/wiki/Almquist_shell https://en.wikipedia.org/wiki/POSIX#POSIX.2 https://en.wikipedia.org/wiki/POSIX#POSIX.2 Bash was introduced in the same year as the Almquist shell. https://en.wikipedia.org/wiki/Bash_(Unix_shell) https://en.wikipedia.org/wiki/Bash_(Unix_shell)