When I'm viewing a page with the source code of a certain file on the "master" or "main" branch, often I want to copy the URL of that file but at its actual commit hash so that it's a permalink.
GitLab makes this super obvious. E.g. https://gitlab.com/gitlab-com/chief-of-staff-team/cos-team/-/blob/master/.gitlab/issue_templates/informal_board_meeting.md shows:
What is the fastest, most convenient way to do the same in Bitbucket?
Its not quick per se, but it is the quickest I've found :-/
Tested on Bitbucket Server v6.10.1
That should give you a shareable permalink.
On Bitbucket Server v6.10.8 (You find your version on the very bottom of any bitbucket page. Maybe this also works for older versions)
Navigate to the file you want to link to e.g. https://bitbucket.com/bitbucket/projects/foo/repos/bar/browse/docker/Dockerfile
In the top right hand corner of the page there should be sentence like: 'Ms. Frizzle authored fb67a3f2efc 07 April 2021 03:16 PM'. Click on this sha checksum.
Click on the sheet icon at the top right of the diff view. 
(in case of multiple file edits in this commit you need to select the wanted file first)
Now you address bar contains the wanted link: https://bitbucket.com/bitbucket/projects/foo/repos/bar/browse/docker/Dockerfile?at=fb67a3f2efc
If you click on a line number of a (source) file, not only the line number becomes part of the current URL, but the respective commit hash as well.
You can stay with the (maybe) superfluous line number or remove it; or remove it together with the file name to generate a permalink for the directory.
