"No Shell"

[David Douthitt]

"Michael Vilain <vilain@spamcop.net>" wrote:

> Just as an aside, if you change HP/UX's root shell to anything other
> than what HP set it to (I vaguely recall setting it to /sbin/ksh rather
> than their braindead non-POSIX /sbin/sh), the system wouldn't shutdown.
> The shutdown command said to change the shell back to /sbin/sh, then run
> shutdown again. I did this on 10.20 some years ago and don't know about
> 11.

I thought both HP-UX 10.20 and 11 used a POSIX sh. Trying to find the
Bourne shell on HP-UX is always fun (sigh).

I would have loved to switch our HP-UX systems to /bin/ksh but I didn't
know enough about the system to do such with impunity - I've heard
enough times the horror stories about not being able to log in and so
forth. When I start wanting more, I always just use the command
"/bin/ksh" and then continue on...

Linux is another matter - I know enough about Linux that I routinely
switch all root accounts to /bin/ksh. Only time it matters is if any of
the startup scripts use a "bash-ism" and don't remember to start their
script with "#!/bin/sh" ...

FreeBSD is yet another matter - I don't know if I could switch root's
shell without problems (their default is /bin/csh) but I don't have to.
There is a user "toor" which is also uid 0 included in FreeBSD for
just such a purpose - change the shell (for "toor" that is) all you
want, that's why "toor" is there.

[jpd]

On 2004-05-19, David Douthitt <ddouthitt@cuna.coop> wrote:

> Linux is another matter - I know enough about Linux that I routinely
> switch all root accounts to /bin/ksh. Only time it matters is if any of
> the startup scripts use a "bash-ism" and don't remember to start their
> script with "#!/bin/sh" ...

Which in itself is bad enough.


--
j p d (at) d s b (dot) t u d e l f t (dot) n l .

[Kevin Collins]

In article <c8g42b$jmv$1@grandcanyon.binc.net>, David Douthitt wrote:

> "Michael Vilain <vilain@spamcop.net>" wrote:
>

>> Just as an aside, if you change HP/UX's root shell to anything other
>> than what HP set it to (I vaguely recall setting it to /sbin/ksh rather
>> than their braindead non-POSIX /sbin/sh), the system wouldn't shutdown.
>> The shutdown command said to change the shell back to /sbin/sh, then run
>> shutdown again. I did this on 10.20 some years ago and don't know about
>> 11.

>
> I thought both HP-UX 10.20 and 11 used a POSIX sh. Trying to find the
> Bourne shell on HP-UX is always fun (sigh).

They do - /sbin/sh is a POSIX sh, /usr/old/bin/sh is Bourne. And HP's /sbin/sh
shares the codebase with /usr/bin/ksh :

$ strings /sbin/sh | grep -i ksh
ksh: Cannot reset line disciplines
ksh: Cannot set line disciplines
ksh: sysconf error
ksh: no memory

And I can't think of anything offhand that can be done with ksh as a user shell
and not be done exactly the same way with /sbin/sh on HP-UX...

>
> I would have loved to switch our HP-UX systems to /bin/ksh but I didn't
> know enough about the system to do such with impunity - I've heard
> enough times the horror stories about not being able to log in and so
> forth. When I start wanting more, I always just use the command
> "/bin/ksh" and then continue on...

It only matters during a system recovery where your filesystems may not be
mounted or your shared libraries are for some reason not accessible. Since
/usr/bin/ksh uses shared libs, it will not work. All executables in /sbin do
not required shared libs, so /sbin/sh is THE shell to use for root.

>
> Linux is another matter - I know enough about Linux that I routinely
> switch all root accounts to /bin/ksh. Only time it matters is if any of
> the startup scripts use a "bash-ism" and don't remember to start their
> script with "#!/bin/sh" ...
>

Since ksh (assuming you mean pdksh) follows the same convention of using shared
libraries under /lib, which should be on th "/" filesystem, that seems pretty
safe.

Out of curiousity, why do you prefer ksh over bash as a user shell? I
personally use ksh as a user shell, but use /bin/bash for root.

> FreeBSD is yet another matter - I don't know if I could switch root's
> shell without problems (their default is /bin/csh) but I don't have to.
> There is a user "toor" which is also uid 0 included in FreeBSD for
> just such a purpose - change the shell (for "toor" that is) all you
> want, that's why "toor" is there.

Kevin

[David Douthitt]

Kevin Collins wrote:

> Out of curiousity, why do you prefer ksh over bash as a user shell? I
> personally use ksh as a user shell, but use /bin/bash for root.

Several reasons:

* Standard: There are no extensions to trip over when I take a Linux ksh
script into a HP-UX or Unixware environment... ksh is standard.

* Clean vi-editing support - everytime I enable vi command history
editing, I find out immediately if I'm in bash or not. Bash gives nasty
prompts and in general acts funny.

* Minimalist: pdksh (or ash, by the way) support nearly everything from
ksh and are much smaller than bash.

* Familiarization: this is personal, and somewhat professional, but I
was programming in ksh (and using csh) before bash came along. I
finally switched to ksh when I started work here as ksh was the standard
shell already and I wanted to learn it (I could have used csh).

[Kevin Collins]

In article <c8gm54$o8m$1@grandcanyon.binc.net>, David Douthitt wrote:

> Kevin Collins wrote:
>

>> Out of curiousity, why do you prefer ksh over bash as a user shell? I
>> personally use ksh as a user shell, but use /bin/bash for root.

>
> Several reasons:
>
> * Standard: There are no extensions to trip over when I take a Linux ksh
> script into a HP-UX or Unixware environment... ksh is standard.

While I generally agree with that, there are differences and incompatibilities
between pure ksh88 and pdksh. The folks who post to this group who are
"portability oriented" would probably disagree more strongly.

> * Clean vi-editing support - everytime I enable vi command history
> editing, I find out immediately if I'm in bash or not. Bash gives nasty
> prompts and in general acts funny.
>
> * Minimalist: pdksh (or ash, by the way) support nearly everything from
> ksh and are much smaller than bash.
>
> * Familiarization: this is personal, and somewhat professional, but I
> was programming in ksh (and using csh) before bash came along. I
> finally switched to ksh when I started work here as ksh was the standard
> shell already and I wanted to learn it (I could have used csh).

Thanks, all valid reasons and ones I mostly share :)

Kevin

[Bill Vermillion]

In article <c8g42b$jmv$1@grandcanyon.binc.net>,
David Douthitt <ddouthitt@cuna.coop> wrote:

>"Michael Vilain <vilain@spamcop.net>" wrote:
>

>> Just as an aside, if you change HP/UX's root shell to anything other
>> than what HP set it to (I vaguely recall setting it to /sbin/ksh rather
>> than their braindead non-POSIX /sbin/sh), the system wouldn't shutdown.
>> The shutdown command said to change the shell back to /sbin/sh, then run
>> shutdown again. I did this on 10.20 some years ago and don't know about
>> 11.

>
>I thought both HP-UX 10.20 and 11 used a POSIX sh. Trying to find the
>Bourne shell on HP-UX is always fun (sigh).

>I would have loved to switch our HP-UX systems to /bin/ksh but I didn't
>know enough about the system to do such with impunity - I've heard
>enough times the horror stories about not being able to log in and so
>forth. When I start wanting more, I always just use the command
>"/bin/ksh" and then continue on...

>Linux is another matter - I know enough about Linux that I
>routinely switch all root accounts to /bin/ksh. Only time it
>matters is if any of the startup scripts use a "bash-ism" and
>don't remember to start their script with "#!/bin/sh" ...

>FreeBSD is yet another matter - I don't know if I could switch
>root's shell without problems (their default is /bin/csh) but
>I don't have to. There is a user "toor" which is also uid 0
>included in FreeBSD for just such a purpose - change the shell
>(for "toor" that is) all you want, that's why "toor" is there.

I've been using /bin/ksh for the root shell on FreeBSD for at least
6 years now. The real ksh, not pdksh.

As to the 'toor' account it is not there to use as an alternate
shell, it's there as a safety net. The default shell for toor is
/bin/sh. The 'toor' entry doesn't even have a shell specified
so you get the default /bin/sh. It's the smallest of all shells
on FreeBSD - at 400K - but all the FreeBSD shells, and all of
/bin for that matter, is statically linked [with the exception of
rmail].

The default root shell on FreeBSD - though called csh is not
the standard csh, but is hard-linked to /bin/tcsh an ehanced
csh.

I'd advise leaving toor completely alone.



--
Bill Vermillion - bv @ wjv . com