From: Sven Wischnowsky <wischnow@informatik.hu-berlin.de>
To: zsh-users@sunsite.auc.dk
Subject: Re: OPTARG not being set?
Date: Wed, 3 Feb 1999 08:38:10 +0100 (MET) [thread overview]
Message-ID: <199902030738.IAA10555@beta.informatik.hu-berlin.de> (raw)
Sweth Chandramouli wrote:
> (astaroth)~1: joe='hello world'
> (astaroth)~2: bob=joe
> (astaroth)~3: echo ${joe}
> hello world
> (astaroth)~4: echo ${bob}
> joe
> (astaroth)~5: echo ${${bob}}
> joe
> (astaroth)~6: echo ${(e)bob}
> joe
> (astaroth)~7: echo "echo \${$(echo ${bob})}"
> echo ${joe}
> (astaroth)~8: `echo "echo \${$(echo ${bob})}"`
> joe
> (astaroth)~9: echo ${ZSH_VERSION}
> 3.1.5
>
> i would think that #5 should print hello world,
> that #6 would explicitly cause parameter expansion and
> print hello world, and that #8 would evaluate the results
> of #7, which would be the same as typing #3, and would
> thus print hello world.
For standard 3.1.5 the syntax with an embedded ${...} inside a ${...}
is only useful if the outer ${...} contains some flags or other
modifying stuff. It will then work on the word(s) produced by the
inner${...}.
The (e) flag means the the string resulting from the whole ${...} will
(at the end) be subject to another expansion (so if you had
bob=\$joe, it would work).
#8 irritates me, especially since:
% $(echo "echo \${$(echo ${bob})}")
yields ${b}. This almost certainly caused by some weird quoting rules,
which may even be documented.
Anyway, you should use eval for this:
% eval echo "\$$bob"
Bye
Sven
--
Sven Wischnowsky wischnow@informatik.hu-berlin.de
next reply other threads:[~1999-02-03 7:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-02-03 7:38 Sven Wischnowsky [this message]
-- strict thread matches above, loose matches on Subject: below --
1999-02-03 18:35 Sweth Chandramouli
1999-02-03 8:23 Bart Schaefer
1999-02-03 8:03 Bart Schaefer
1999-02-03 3:56 Sweth Chandramouli
1999-02-02 8:52 Bernd Eggink
1999-02-02 5:54 Sweth Chandramouli
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