[ ! ! hey ] -> [: too many arguments
Hello. 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 (The single ! that my MUA bails on seems to be handled identically by shells.) --steffen | |Der Kragenbaer,The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt)
Re: [ ! ! hey ] -> [: too many arguments
Steffen Nurpmeso wrote in <20220623133946.h72dj%stef...@sdaoden.eu>: ... | #?0|kent:tmp$ bash -c 'if [ ! ! hey ]; then echo du; fi' | bash: line 1: [: too many arguments (5.1.16 that is on CRUX ports/core/bash/Pkgfile ./configure \ --prefix=/usr \ --exec-prefix= \ --disable-nls \ --with-curses \ --with-installed-readline make -j1) --steffen | |Der Kragenbaer,The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt)
Re: [ ! ! hey ] -> [: too many arguments
On 6/23/22 9:39 AM, Steffen Nurpmeso wrote: Hello. 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. Chet -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, UTech, CWRUc...@case.eduhttp://tiswww.cwru.edu/~chet/
Re: [ ! ! hey ] -> [: too many arguments
Chet Ramey wrote in <4169f2cd-d81c-29b7-918c-156b447c5...@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. (P.S.: but mind you, the times when i used to say, give it to me, if i cannot break it that is a good sign, they have long passed. You have to walk to stumble that is. Ciao.) --steffen | |Der Kragenbaer,The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt)
Re: [ ! ! hey ] -> [: too many arguments
On 6/23/22 5:08 PM, Steffen Nurpmeso wrote: Chet Ramey wrote in <4169f2cd-d81c-29b7-918c-156b447c5...@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, CWRUc...@case.eduhttp://tiswww.cwru.edu/~chet/
Re: [ ! ! hey ] -> [: too many arguments
On 22/06/23 11:08 PM, Steffen Nurpmeso wrote: > or even > bash -c 'if [ ! ! hey = hey ]; then echo du; fi' > bash -c 'if [ ! false = 1 ]; then echo du; fi' `! ! hey = hey' is the same as `! ( ! ( hey = hey ) )', so "not not true => true". It probably works correctly because `! ! hey = hey' are five terms. The bug only occurs for 3 or 4 terms tests: bash-5.1$ test ! ! hey ; printf %s\\n "$?" bash: test: too many arguments 2 bash-5.1$ test ! ! ! hey ; printf %s\\n "$?" bash: test: too many arguments 2 bash-5.1$ test ! ! ! ! hey ; printf %s\\n "$?" 0 bash-5.1$ test ! ! ! ! ! hey ; printf %s\\n "$?" 1 test(1) needs to treat the 0 to 4 arguments expressions specially according to POSIX so the bug is probably only in the code that implements those special cases. -emanuele6
Re: [ ! ! hey ] -> [: too many arguments
On Thu, Jun 23, 2022 at 05:58:23PM -0400, Chet Ramey wrote:
> On 6/23/22 5:08 PM, Steffen Nurpmeso wrote:
> >bash -c 'if [ ! ! hey = hey ]; then echo du; fi'
> Sure. This one isn't a common idiom for shell programmers, apparently.
I've seen it used in a math context, inside PS1. Like so:
color=(
"$(tput setaf 2)" # 0 = green
"$(tput setaf 1)" # 1 = red
)
normal="$(tput sgr0)"
PS1='\[${color[!!$?]}\]$?\[$normal\] \h:\w\$ '
This writes the previous command's exit status in either green or red.
It "smashes" all nonzero exit codes to 1, using a double negation in
a C-style arithmetic context, in order to generate an array index for
the color.
I don't recall ever seeing it used in the way Steffen showed, though.
