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Double substitution issue

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  Double substitution issue William Entriken <fulldecent@gmail.com> - 2018-02-28 03:25 -0500
    Re: Double substitution issue fulldecent@gmail.com - 2018-11-20 20:16 -0800
      Re: Double substitution issue Greg Wooledge <wooledg@eeg.ccf.org> - 2018-11-21 08:37 -0500

#13766 — Double substitution issue

This behavior is different in zsh and bash, and maybe bash behavior is a
bug.

# Test case

touch 1 2 3
cat > script.sh <<EOL
from=1
to=3
ls {$from..$to}
EOL
chmod a+x script.sh

bash ./script.sh

zsh ./script.sh

# Expected

Both list files 1, 2, 3

# Actual

zsh passes.

Bash fails the chained substitution with:

ls: {1..3}: No such file or directory

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#14837

Thank you for explaining this fine point. 

I have found a way to use double expansion, and of course this is not safe 
in all contexts: 

    from=1;to=3;eval echo {$from..$to} 

Regards, 
Will 

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#14838

On Tue, Nov 20, 2018 at 08:16:47PM -0800, fulldecent@gmail.com wrote:
> I have found a way to use double expansion, and of course this is not safe 
> in all contexts: 
> 
>     from=1;to=3;eval echo {$from..$to} 

for ((i=from; i<=to; i++)); do
  ...
done.

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