Is there such a thing?
If no, what is the keystroke to select the entire current line?
I don’t know that there is such a thing, but you can select the entire current line and then hit Delete:
Your question is rather vague on the definition of “line” because a line, like a page, is not a primary object in a document. A line is a consequence of layout. Change some settings (margins, font family or size, …) and the content of a line is different.
I’ll first take line with the common meaning.
If the challenge is to do everything from the keyboard, hit Start (key may also be marked with a NW-pointing arrow) – cursor goes to the beginning of line --, then Shift+End (key may also be marked with a SE-pointing arrow) – selection extends to end of line) and finally hit Backspace or Del.
If you consider another definition of “line” and accept to use the mouse, here are the possibilities:
- double-click selects the word the cursor is in
- triple-click selects the current sentence
- quadruple-click selects the current paragraph
IMHO, word, sentence and paragraph are more meaningful in diocument context.