Re: Turn history saving on by default? (Re: GDB BoF notes - GNU Cauldron 2023)

[Guinevere Larsen via Gdb <gdb@sourceware.org>]

On 29/09/2023 11:52, Pedro Alves wrote:
> On 2023-09-29 10:24, Lancelot SIX wrote:
>>>> - Revisiting defaults
>>>>
>>>>     - Can we turn history saving on by default?  Maybe default to
>>>>       history on home dir by default, too (~/.gdb_history).  That would
>>>>       align us with bash.  Some in the room have had this enabled in
>>>>       their gdbinits for so long they no longer remembered this wasn't
>>>>       on by default.  Others weren't even aware you can turn this on.
>>> One issue I find with the bash approach is that you end up mixing history
>>> between multiple unrelated sessions. Bash can't solve this but GDB possibly
>>> could.
>>>
>>> My suggestion would be to use an approach similar to vim's swap files. As an
>>> example, editing the maintainers file, I have the file ~/.local/state/nvim/swap/%home%blarsen%Documents%binutils-gdb%gdb%MAINTAINERS.swp;
>>> This way you can have histories specific to any binary you're debugging
>>> without mixing sessions.
>>>
>> Hi,
>>
>> With such approach, I am not really sure how to name/identify a session.
>> Is that based on the name of the binary you're debugging?  If so what
>> happens if you use `file another_bin`?  Either you switch to another
>> "session", but really you never left GDB so that would seem odd to me,
>> or you end up having history about another_bin in your first apparently
>> unrelated session.
> Of what happens if you start GDB without a binary at all?
Yeah, those are good points. Any way to fix this is way over-engineering 
compared to just "local histories in each folder".
>
>> Similarly, when dealing with multiple inferiors, would running `inferior
>> N` switch from session to session?
>>
>> I can see cases where such behavior could be helpful, but there seems
>> to be a lot of edge cases where it could become strange.
>>
>> My feeling for now is that the best way to achieve this is to save the
>> gdb history in the current directory, with the "risk" of having plenty
>> of history files left all-over the place (as you mentioned already).
>>
>> I feel that having the default somewhere under $HOME / $XDG_STATE_HOME
>> (as suggested by Tom) seems an "easier" default.
>>
> My thoughts exactly.  +1.
>
> On my bash for example, I got recently annoyed with
> all my ssh shells overwriting the same history file, so I came up with a way to
> have easy separate bash history sessions.  But, I still think that the bash default
> is OK.
>
> The only viable options that I can think of for gdb are:
>
> #1 - don't save history  (current default)
> #2 - save history in current dir
> #3 - save history in $HOME (or somewhere XDG if it makes system for the system)
>
> #1 is of course the current default.
>
> #2 is what I do in my .gdbinit:
>
>   set history save on
>   set history filename .gdb_history
>   set history size unlimited
>
> This works well enough for me.  It does have the downside of sprinkling .gdb_history files all
> over the place, which gets a bit annoying at times.  E.g., sometimes I'll spawn gdb in a random
> directory because I often use gdb as my calculator :-)  ("(gdb) p 1 + 2 * 3", etc.),
> which ends up with a .gdb_history file in that dir.  Still, it's my choice, and
> I am aware of the consequences.
>
> #3 seems like a reasonable default to me, which doesn't have that "sprinkle files
> throughout the filesystem" issue.
>
Yeah, I think I agree. This can still be over-written by a user that 
wants separate histories, and having mixed ones is better than nothing 
at all. +1 for making 3 the default

-- 
Cheers,
Guinevere Larsen
She/Her/Hers