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Re: [Help-bash] Bash is corresponding weird towards invalid array index-
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From: |
Greg Wooledge |
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Subject: |
Re: [Help-bash] Bash is corresponding weird towards invalid array index--Gao 2017.6.2 |
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Date: |
Fri, 2 Jun 2017 09:49:09 -0400 |
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User-agent: |
Mutt/1.4.2.3i |
On Fri, Jun 02, 2017 at 08:15:15PM +0800, Zhiyuan Gao wrote:
> $array_1[0]=123
> $array_1[1]=456
> $array_1[2]=789
> $echo
> ${array_1[99999999999999999999999999999999999999999999999999999999999999999999]}
>
> It actually returned 789!
Looks like integer overflow to me. Array indices are 64-bit integers,
and you've exceeded that range.
imadev:~$ unset a
imadev:~$ a[2]=789
imadev:~$ echo "${a[2]} ${a[18446744073709551618]}"
789 789
You just got really (un)lucky with your string of 9s happening to map
back to 2, modulo 2^64.