RegExp in search field

[Format C:]

The problem: select all authors whose last name begins with "A".
Easy solution: select each one of them form the tag browser (Calibre does not seem to permit the selection from a grouped tag branch).

I'm actually looking for a more general solution, so I tried to search with regular expressions, with no luck.

The first problem I incurred into is the incredible persistence of previously used searches: the first attempt I made, I accidentally wrote it with a lowercase "a" instead of the capital one. Now, there's no way to use the same expression with the correct case. No matter how I try, Calibre will always get the previous lowercase one.

Another annoyance is that whatever I type in the search field after the colon ":" is interpreted as a command. So, when I try to type "author_sort:A" I end up with the "add files dialog". As soon as I remember my password, I'll open a bug for that...

Getting back to regular expression, I've used the advanced search function and the search field in the library, with the same result: nothing selected.
Here are my attempts:

author_sort:A --> I got all the authors with an "A" somewhere in their names (case insensitive)

author_sort:^A --> Empty list
author_sort:=^A --> Empty list
author_sort:"^A" --> Empty list
author_sort:="^A" --> Empty list

Putting ".+" after the cited RE does not change anything.

So, what can I do to restrict the library to authors whose last name begins with a specified letter (or one from a set of such letters)?

Thank you for your help!

[kiwidude]

author_sort:"~^A.*"

Use Preferences->Searching to clear your search history

[Format C:]

It works, thank you kiwidude.

[Starson17]

Originally Posted by Format C:

The problem: select all authors whose last name begins with "A".

This was already answered, but in case it's not clear, the first character after fieldname:" tells calibre what to do.
fieldname:"~ means use regex
fieldname:"= means exact match

The first problem I incurred into is the incredible persistence of previously used searches: the first attempt I made, I accidentally wrote it with a lowercase "a" instead of the capital one. Now, there's no way to use the same expression with the correct case. No matter how I try, Calibre will always get the previous lowercase one.

1) You can delete old searches as described above.
2) FYI, searches are case insensitive
3) I dislike the search as you type option - it can be turned off in Preferences

Another annoyance is that whatever I type in the search field after the colon ":" is interpreted as a command. So, when I try to type "author_sort:A" I end up with the "add files dialog". As soon as I remember my password, I'll open a bug for that...

Odd. I don't see this.

Getting back to regular expression, I've used the advanced search function and the search field in the library, with the same result: nothing selected.
Here are my attempts:

author_sort:A --> I got all the authors with an "A" somewhere in their names (case insensitive)

author_sort:^A --> Empty list
author_sort:=^A --> Empty list
author_sort:"^A" --> Empty list
author_sort:="^A" --> Empty list

Putting ".+" after the cited RE does not change anything.

As above - none of those are regexes.

[Format C:]

Thank you everybody.
I missed the tilde for the input of regexp...