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Groups > comp.unix.shell > #26926

Re: Variable var names

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 Kaz Kylheku <046-301-5902@kylheku.com>:

> It is also written that "If the command name is a special 
> built-in utility, variable assignments shall affect the current 
> execution environment before the utility is executed and remain 
> in effect when the command completes". So in fact ksh is 
> conforming, even though it is arguably a dumb behavior that Bash 
> disagrees with (even in --posix mode; just tested with 4.4 and 
> 5.1). 
>

 Interesting.  In my Debian Linux system, “bash” 


   + bash --version
   GNU bash, version 5.1.4(1)-release (i686-pc-linux-gnu)
   Copyright (C) 2020 Free Software Foundation, Inc.
   License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

   This is free software; you are free to change and redistribute it.
   There is NO WARRANTY, to the extent permitted by law.


 obeys the POSIX standard in --posix mode as well as when invoked 
 with the name “sh”:  The “bash” command 


   (
     cmdline='
       unset -v foo &&
       foo=bar eval : &&
       if ${foo+:} false
       then
         printf %s\\n posixly
       else
         printf %s\\n not\ posixly
       fi' &&
     for invocation in \
       "$(
         printf ' %q' \
         exec -a bash -- bash -c "$cmdline" bash
       )" \
       "$(
         printf ' %q' \
         exec -a bash -- bash --posix -c "$cmdline" bash
       )" \
       "$(
         printf ' %q' \
         exec -a sh -- bash -c "$cmdline" sh
       )"
     do
       eval set -- "$invocation" && echo &&
       ( set -x && "$@" )
     done
   )


 yields the following output: 


   + exec -a bash -- bash -c '
          unset -v foo &&
          foo=bar eval : &&
          if ${foo+:} false
          then
            printf %s\\n posixly
          else
            printf %s\\n not\ posixly
          fi' bash
   not posixly

   + exec -a bash -- bash --posix -c '
          unset -v foo &&
          foo=bar eval : &&
          if ${foo+:} false
          then
            printf %s\\n posixly
          else
            printf %s\\n not\ posixly
          fi' bash
   posixly

   + exec -a sh -- bash -c '
          unset -v foo &&
          foo=bar eval : &&
          if ${foo+:} false
          then
            printf %s\\n posixly
          else
            printf %s\\n not\ posixly
          fi' sh
   posixly

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Variable var names Frank Winkler <usenet@f.winkler-ka.de> - 2026-06-12 09:30 +0200
  Re: Variable var names gazelle@shell.xmission.com (Kenny McCormack) - 2026-06-12 09:02 +0000
    Re: Variable var names Frank Winkler <usenet@f.winkler-ka.de> - 2026-06-13 12:29 +0200
      Re: Variable var names gazelle@shell.xmission.com (Kenny McCormack) - 2026-06-13 11:14 +0000
      Re: Variable var names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-06-13 13:15 +0200
  Re: Variable var names ram@zedat.fu-berlin.de (Stefan Ram) - 2026-06-12 11:26 +0000
    Re: Variable var names ram@zedat.fu-berlin.de (Stefan Ram) - 2026-06-12 11:38 +0000
      Re: Variable var names Frank Winkler <usenet@f.winkler-ka.de> - 2026-06-12 14:07 +0200
        Re: Variable var names ram@zedat.fu-berlin.de (Stefan Ram) - 2026-06-12 12:31 +0000
          Re: Variable var names Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-06-13 02:48 +0000
  Re: Variable var names Christian Weisgerber <naddy@mips.inka.de> - 2026-06-12 12:12 +0000
    Re: Variable var names Frank Winkler <usenet@f.winkler-ka.de> - 2026-06-12 15:19 +0200
    Re: Variable var names Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-06-13 02:51 +0000
  Re: Variable var names Geoff Clare <geoff@clare.See-My-Signature.invalid> - 2026-06-12 13:42 +0100
  Re: Variable var names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-06-12 17:41 +0200
    Re: Variable var names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-06-12 17:54 +0200
    Re: Variable var names Frank Winkler <usenet@f.winkler-ka.de> - 2026-06-13 12:32 +0200
      Re: Variable var names Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-06-14 01:12 +0000
  Re: Variable var names Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-06-13 00:20 +0000
  Re: Variable var names Kaz Kylheku <046-301-5902@kylheku.com> - 2026-06-23 21:25 +0000
    Re: Variable var names Helmut Waitzmann <nn.throttle@erine.email> - 2026-06-24 10:45 +0200
    Re: Variable var names Christian Weisgerber <naddy@mips.inka.de> - 2026-06-24 11:41 +0000

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