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Re: \! and \# in PS1 vs PS2 vs PS4, PS0 and address@hidden

From: Chet Ramey
Subject: Re: \! and \# in PS1 vs PS2 vs PS4, PS0 and address@hidden
Date: Sat, 18 Mar 2017 15:21:39 -0400
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:45.0) Gecko/20100101 Thunderbird/45.8.0

On 3/17/17 5:43 PM, Grisha Levit wrote:

> Fair enough; sorry for the vague report.  I thought it was surprising that:
> 1. \! and \# increment at different times during command entry

OK, I see what you mean.  They are incremented at different times, and by
different "agents". The command number (\#) is incremented after the shell
parses a complete command and before it is executed.  The history number
(\!) increments when the first line of the command is read and returned and
bash calls add_history.  It's the result of the division of responsibility
between bash and readline.  The shell is the one responsible for adding
subsequent lines to the first history entry (`command-oriented history'),
so the history library has done it's job: it's incremented the history
number and is waiting for the next call to add_history().

Maybe the shell could special-case \! for the second and subsequent lines
of a multi-line command, but that seems tricky to get right.

How would you suggest capturing this in the documentation in a way that
would be clearer?  The text from your previous message or something else?

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

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