Scott Robbins wrote:
On Tue, Apr 26, 2016 at 07:27:26PM -0700, Alice Wonder wrote:
Some of the BSDs use to have a bourne shell and maybe some do, I don't
know.
Yup.
bash is mostly compatible with bourne (can run most bourne scripts)
which is why /bin/sh is a symlink to /bin/bash on GNU and most other *nix systems.
Bash can run Bourne, but not necessarily vice versa, which can be
problematic if, say, moving a Linux script to a BSD or AIX box. I remember something I'd done which used, IIRC, $UID, without realizing it was a bashism, instead of using id -u.
I'll also note that all *production* scripts were once required to be bourne, but by the mid-ninties, management was starting to mandate that they be Korn shell, instead, for many reasons - capabilities, etc. Bash - I don't think I saw that till I started running RH 5.1, I think it was, about 18 years ago....
mark
On Wed, April 27, 2016 10:01 am, m.roth@5-cent.us wrote:
Scott Robbins wrote:
On Tue, Apr 26, 2016 at 07:27:26PM -0700, Alice Wonder wrote:
Some of the BSDs use to have a bourne shell and maybe some do, I don't
know.
Yup.
bash is mostly compatible with bourne (can run most bourne scripts)
which is why /bin/sh is a symlink to /bin/bash on GNU and most other *nix systems.
Bash can run Bourne, but not necessarily vice versa, which can be
problematic if, say, moving a Linux script to a BSD or AIX box. I remember something I'd done which used, IIRC, $UID, without realizing it was a bashism, instead of using id -u.
There is at least one good reason Bourne shell is still alive and not striving to cover all Bourne-Again shell (bash) features IMHO. Bourne shell is very well debugged, and code is much smaller, hence much less chance to have undiscovered bugs. Therefore, it should be much better security wise. Imagine you never heard about shellshock, and I ask you is it bash or is it Bourne shell, what would you bet be? (90 or 95% it is bash would be mine, - if I recollect correctly my reaction when I first heard about that).
Just my $0.02
Valeri
I'll also note that all *production* scripts were once required to be bourne, but by the mid-ninties, management was starting to mandate that they be Korn shell, instead, for many reasons - capabilities, etc. Bash - I don't think I saw that till I started running RH 5.1, I think it was, about 18 years ago....
mark
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++++++++++++++++++++++++++++++++++++++++ Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ++++++++++++++++++++++++++++++++++++++++
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Valeri Galtsev