Re: [ ! ! hey ] -> [: too many arguments

[Chet Ramey]

On 6/23/22 5:08 PM, Steffen Nurpmeso wrote:
> Chet Ramey wrote in
>   <4169f2cd-d81c-29b7-918c-156b447c5220@case.edu>:
>   |On 6/23/22 9:39 AM, Steffen Nurpmeso wrote:
>   |> I stumbled over a bug in the MUA i maintain, and when checking
>   |> against what shells do with lonely unary ! i then came to this:
>   |>
>   |>    #?0|kent:tmp$ dash -c 'if [ ! ! hey ]; then echo du; fi'
>   |>    du
>   |>    #?0|kent:tmp$ bash -c 'if [ ! ! hey ]; then echo du; fi'
>   |>    bash: line 1: [: too many arguments
>   |>    #?0|kent:tmp$ busybox.static sh -c 'if [ ! ! hey ]; then echo du; fi'
>   |>    du
>   |
>   |Thanks for the report. This appears to have existed for over thirty years,
>   |and you're the first one to report it.
>
> Hey.  For a C programmer things like
>
>    bash -c 'if [ ! hey = hey ]; then echo du; fi'
> or even
>    bash -c 'if [ ! ! hey = hey ]; then echo du; fi'
>    bash -c 'if [ ! false = 1 ]; then echo du; fi'
>
> seem often more strange .. and is handled the same by all above
> shells.

Sure. This one isn't a common idiom for shell programmers, apparently.


--
``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/