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Re: Substring expansion error when offset contains a colon
From: |
Chet Ramey |
Subject: |
Re: Substring expansion error when offset contains a colon |
Date: |
Mon, 26 Oct 2015 09:19:09 -0400 |
User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 |
On 10/19/15 3:45 AM, grishalevit@gmail.com wrote:
> When using ${parameter:offset:length} expansion, the parser doesn't account
> for all the ways that a colon can appear in "offset".
>
> For example:
>
> $ echo ${PARAM:${OFFSET:-0}}
> -bash: ${OFFSET: bad substitution
>
> or:
>
> # declare -A A=([a:b]=0)
> # echo ${PARAM:${A[a:b]}}
> -bash: ${A[a: bad substitution
>
> It seems that the issue is in the use of skiparith in
> verify_substring_values. Switching to to skip_to_delim removes this issue.
> The ${parameter/pattern/string} expansion uses skip_to_delim to search for
> the second '/' so I suspect it's use is appropriate here as well.
It's not quite that simple. The reason skiparith() is used is that
arithmetic expressions may contain a colon (test?exp1:exp2), so skiparith
skips over one colon for each `?'. I will have to figure out a way to
continue to support this syntax for backwards compatibility and allow for
colons in other contexts.
Chet
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU chet@case.edu http://cnswww.cns.cwru.edu/~chet/