UNIX for Advanced & Expert Users

I like bash then ksh then sh

Hi,

I use bash shell at my home,but I use ksh at office. But most of the IT organizations use korn shell for scripting and other unix related activities, even if every facilities of ksh are also available in bash.

Could anyone please explain why it organizations prefer korn shell instead of bash shell. Thanks!

Kind regrads,

OK, just one of the most annoying differences.

Suppose the following command lines, which could also be part of a script:

Code:

# mkdir kshtest ; cd kshtest ; touch a ; touch b ; touch c
# typeset x=""
> ls | while read y ; do
>      x="$x $y"
>      echo "$x"
> done
> echo "$x"

What is the content of "$x" after the loop? I every programming language i know (and ksh as well) it is "a b c". In bash it will be "" (empty string), because the content of "$x" is somewhat local to the code block. Notice the difference in the first "echo $x" and the last line.

Of course it would be possible to prevent this by replacing the pipeline with a redirection:

Code:

# mkdir kshtest ; cd kshtest ; touch a ; touch b ; touch c
# typeset x=""
> while read y ; do
>      x="$x $y"
>      echo "$x"
> done < "$(ls)"
> echo "$x"

but i would like my while-loops not to be steered at the bottom. It is just hard to read if the loop is longer and you have to go three pages down to find out what is fed into the loop, then go back up to see what is done with the input.

bakunin

Portability and availability.
Many unix Operating Systems do not come with bash.
There are non-standard scripting language extensions in bash.

This is incorrect, ksh has several features bash doesn't implement (and reciprocally). Some I'm missing in bash are:
- co-processes
- FPATH
- floating-point arithmetic (ksh93)
- discipline functions (ksh93)
Also, I find very annoying how command history is handled in bash.
A mixture of cleverness, pragmatism and inertia ...

---------- Post updated at 15:17 ---------- Previous update was at 14:50 ----------

Instead of

Code:

done < "$(ls)"

which makes a syntax errror, you probably want:

Code:

done < <(ls)

or

Code:

done <<< "$(ls)"

or even better because portable (POSIX):

Code:

done << %EOF%
$(ls)
%EOF%

While I share your opinion about the unfortunate bash implementation choice regarding the pipeline subshell, I have to admit ksh behavior is not guaranteed by POSIX, it is just an accepted extension. Portable scripts shouldn't rely on it.

I get tired of hearing ksh being called "portable" when it's available almost nowhere I go unless I install it myself, and people keep banging their heads on ancient versions which have almost none of the features people like so much about ksh.

If you want shell code to be portable and available, program for neither bash nor ksh, which contain mutually exclusive features, and neither are available everywhere. Program for posix SH.

Which of the many Posix standards would you chose?

Ps. Veiled in the original question was the implication that ksh was available on all that organisation's servers.