Re: [PATCH 5/5] Add "save history" command

[Pedro Alves <pedro@palves.net>]

On 2023-01-30 2:50 p.m., Pedro Alves wrote:
> On 2023-01-29 4:21 p.m., Tom Tromey wrote:
>>  
>> +@kindex save history
>> +@item save history @var{filename}
>> +Occasionally you may want to save your history to a file.  This
>> +command will do just that, saving the commands in your current session
>> +to the named file.  Note that you should normally edit the saved
>> +history before using @code{source} to reload it, as the @code{save
>> +history} command itself will be at the end of the file.
> 
> We could also suggest using "server save history" here.  Something like,
> "Alternatively, you can use the server prefix to blah, blah.  @xref."
> 
> Prefixing a comment with "server" makes it so that it won't be added to
> the history:
> 
>   https://sourceware.org/gdb/current/onlinedocs/gdb.html/Server-Prefix.html
> 

An alternative idea would be to make use of the fact that history entries are
already numbered, and to let the user say which history entry range to save.

E.g., we have:

 (gdb) help show commands 
 Show the history of commands you typed.
 You can supply a command number to start with, or a `+' to start after
 the previous command number shown.

and, e.g., I see currently:

 (gdb) show commands 
  1016  q
  1017  q
  1018  p 1
  1019  p 2
  1020  p 3
  1021  show commands
  1022  p 4
  1023  p 5
  1024  apropos history
  1025  show commands 

so we could support something like:

 (gdb) save history $filename 1020 1025  # save from 1020 to 1025

 (gdb) save history $filename 1020       # save from 1020 to $end

 (gdb) save history $filename -5         # save from 1020 ($last - 5) to end

 (gdb) save history $filename -5 -1      # save from 1020 ($last - 5) to 1024 ($last - 1)

or whatever other syntax makes sense and achieves a similar effect.

Being able to save just the last N entries seems like a useful feature.