[colug-432] Why Bourne Shell Compatible: Portability

[Rob Funk]

On Wednesday, August 10, 2011 12:30:32 PM Chris Clonch wrote:
>  I was shocked when I discovered that /bin/sh linked to something other
>  than the bourne shell.  This small discovery later lead to my
>  understanding that practically all Linux distro's seem do this.  I guess
>  it makes sense as most *sh shells are backwards complaint with sh.  But
>  my assumption that shebanging /bin/sh got me the plain ole original is
>  not correct.  And, well, we all know what happens when you assume...

The actual Bourne shell doesn't even exist on any non-commercial Unix/Linux, 
since it's AT&T code. The closest we get is ash or dash, which were intended 
to be basic Bourne-compatible shells with no extra bells and whistles.

bash is the "Bourne-Again Shell", originally designed by the GNU people to be 
compatible with the original Bourne shell, but extend it. I think bash may 
also try to be compatible with the Korn Shell (also AT&T code, though there's 
a "pdksh" clone, and also intended to be Bourne-compatible).

Then there are csh and tcsh, which were influential on bash but are completely 
different and incompatible.