Can I batchly set tags in org mode?

Question

Suppose I have hundreds lines of items:

**** aa
**** bb
......
**** cc

I try to multiply set tags. I tried to mark them, and use C-c C-q, but it didn't works

Answer 1

As org files are plain text files, we can add tags using a simple approach: query-replace-regexp.

1. Go to the beginning of the buffer.
2. Do M-x query-replace-regexp or use the default binding C-M-%.
3. Enter regexp to match the org headings: ^\*+\s-+.*
4. To add a tag, you basically append the heading with a space, a : and the tag.
   So the replacement text would be \& :MYTAG. Here \& represents whatever text was matched in the "search" step above.
5. Now you can review and hit yes only where you want the tag to be appended, or just hit ! if you want to append tags to all the org headings in the buffer.

---

Here's an example org buffer:

* abc
** def
*** ghi
* jkl
** mno

By implementing the above steps and hit ! in that last step, that would get converted to:

* abc :MYTAG
** def :MYTAG
*** ghi :MYTAG
* jkl :MYTAG
** mno :MYTAG

Answer 2

If the headlines you want to change tags for are all located in a contiguous region you can highlight them all, and then use the org-change-tag-in-region command.

Answer 3

org-agenda supports many bulk actions. Do an org-agenda search (C-c a) that matches the entries you're interested in. In the agenda view use m to mark them (or * to mark everything) and the B to select a bulk action. The + action will add a tag to each entry.