bug-bash
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Issues with history substitution and its documentation


From: Chet Ramey
Subject: Re: Issues with history substitution and its documentation
Date: Mon, 18 Nov 2019 10:34:47 -0500
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.2.2

On 10/3/19 6:19 PM, Jim Monte wrote:

Description:
=============================================================================
Documentation of quick substitution is incorrect (or does not match
behavior).

I believe this issue is an error with the documentation of history
"Quick Substitution" that has existed since the first snapshot available at
web.archive.org in 2007 at

https://web.archive.org/web/20071223174140/http://www.gnu.org/software/bash/manual/html_node/Event-Designators.html

At the least it is true that bash does not behave as the documentation
states,
but it does act in a way that is more reasonable (to me) than what is
written.

The documentation states that ^string1^string2^ is equivalent to
!!:s/string1/string2/. However, bash treats it as equivalent to
!!:s^string1^string2^.

This is correct, and I changed the documentation.

=============================================================================
Behavior of empty "old" string in a substitution is undefined.

The earlier example also shows a related but different issue with the
!!:s//a/b/ command, where the string to locate is empty.
It causes /a to be replaced by a and the b/ is appended.

It's not, actually. It's documented in the man page, but due to an
oversight the text doesn't appear in the texinfo manual.


=============================================================================
BUG
If an event designator has a leading - character, it is ignored.

It's treated as an offset with value 0, and otherwise ignored. If it's not
followed by a digit string, it should be treated as part of a search
string.

Chet

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



reply via email to

[Prev in Thread] Current Thread [Next in Thread]