Re: syntax error with lone > or < as string in [ ] tests with -a or -o operators

[Chet Ramey]

On 4/14/24 5:16 AM, Emanuel Attila Czirai wrote:

> Bash Version: 5.2
> Patch Level: 26
> Release Status: release
>
> Description:
>      the [ test with -n or -z on a string that's only the angle bracket char
> followed by -a or -o operators, fails like:
> bash: [: syntax error: `-n' unexpected
>
> Repeat-By:
>
> $ [ -n ">" -a -n "something" ] || echo hmm
> bash: [: syntax error: `-n' unexpected
> hmm

I think the part your analysis is missing is that `<' and `>' are binary
operators, so this really is an ambiguous expression.

POSIX test specifies what happens when there are four or fewer arguments
(and the upcoming issue 8 will remove -a/-o/(/) altogether); when you
have more than four you're dealing with historical algorithms. Historical
parsing gave the string comparison binary operators higher precedence than
the unary operators.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/

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