Re: BASH_COMMAND should be set before PS0

[Chet Ramey]

On 3/19/22 1:07 PM, Taqras via Bug reports for the GNU Bourne Again SHell 
wrote:

> Bash Version: 5.1
> Patch Level: 16
> Release Status: release
>
> Description:
>      PS0:
>        The value of this parameter is expanded like PS1 and displayed by
>        interactive shells after reading a command and before the command is
>        executed.
>      BASH_COMMAND:
>        The command currently being executed or about to be executed, unless
>        the shell is executing a command as the result of a trap, in which
>        case it is the command executing at the time of the trap. If
>        BASH_COMMAND is unset, it loses its special properties,
>        even if it is subsequently reset.
>      PROBLEM:
>        By the time PS0 is displayed, BASH_COMMAND is still set to the
>        previous command, not the command about to be executed.

These two events take place at different points in command processing. PS0
is displayed immediately after the shell reads a command. BASH_COMMAND is
set after assignment statements and redirections are processed as part of
command execution. You can't reconcile these two things.

--
``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/