Subject: Re: [ksh93-integration-discuss] CR 6977405 Created, P4 shell/korn93
ksh93 script has problem with newline
--------
> === *Description* ============================================================
> Such simple script like:
>
> #!/bin/sh
>
> set -vx
> COMMAND="/usr/bin/echo
> -d passwd"
>
> echo "$COMMAND"
>
>
> has very strange output:
>
> $ ./testbug.sh
> COMMAND="/usr/bin/echo
> -d passwd"
>
> + COMMAND=$'/usr/bin/echo \n-d passwd'
> echo "$COMMAND"
> + echo $'/usr/bin/echo \n-d passwd'
> /usr/bin/echo
> -d passwd
>
>
> "$'/usr/bin/echo \n-d passwd' is different from other shells and it is used
> only
> in case that there is newline (and other shells probably).
>
> From ksh93 FAQ:
>
> Q5. What is the purpose of $'...'?
> A5. The $'...' option was added to ksh93 to solve the problem
> of entering special characters in scripts. It uses
> ANSI-C rules to translate the string between the '...'.
> It would have been cleaner to have all "..." strings handle
> ANSI-C escapes, but that would not be backwards compatible.
>
>
> Well, this is incompatible with other shells, misleading and awkward.
>
> *** (#1 of 1): 2010-08-16 15:42:38 GMT+00:00 <User 1-1SURPB>
>
>
> === *Public Comments* ========================================================
>
>
I don't see or understand what the problem is.
ksh93 is a reflexive language. As much as possible, the output format is
in a form that can be reinput. To avoid confusion, ksh93 uses the $'...'
on output knowing that it can be copied back as input.
There reflexive nature of ksh93 can be see with variabesl (including compound
variables) and types for which which.
typeset -p > file
produces a file you you can do
. file
and get back all the variables and attributes (except readonly).
I don't know what other shells offer this, but this is an important feature
for ksh93.
David Korn
d...@research.att.com
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