Is there a way to search tag header without agenda in org-mode?

Question

All information over the internet about searching tags in the org-mode says about C-c a m Match a TAGS/PROP/TODO query in org-agenda

I have many org files which are not in the agenda file (not in org-agenda-files).

I just wonder (at least) if it shows only headlines having a specific tag in a buffer or files without the help of agenda.

Answer 1

Assuming that you want to search for tags in the current buffer only, you can do C-c \ (bound to org-match-sparse-tree) with a match expression as argument, as defined in Matching tags and properties in the manual. For example, to search for items with tag foo, you say: C-c \ +foo; if you want to find items with tags foo and bar, you say: C-c \ +foo+bar; if you want to find items with tag foo but not with tag bar, you say C-c \ +foo-bar - and so on... All of these will give you a sparse-tree view of the hits.

You can also, of course, just use standard emacs text searches, e.g. C-s :foo: (assuming that there is no text :foo: in your Org mode file that is not a tag - otherwise, you'll get a false positive). After all, Org mode files are just text files.

If you want to search through multiple files, there are many ways (e.g. multi-occur or multi-occur-matching-buffers, dired and relatives, etc), all of which involve some way of selecting the files/buffers of interest and then applying a (fixed or user-provided) function to each one. It's impossible to suggest a "solution" without specifying the problem much more precisely than you have.