Emacs

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_posts/2022-09-14-emacs.md

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+---
+layout: post
+title:  "Emacs Basics"
+date:   2022-09-14 09:13:00 +0100
+categories: tools
+---
+
+## Basics
+
+Emacs is a text editor with command line interface. It allows to edit a text
+using only keyboard. You can write text on it as usual and perform "shortcuts"
+to perform some actions with the editor and the text.
+
+These "shurtcuts" are called commands.
+
+```
+C-x C-c Close the editor.
+```
+To perform this command you have to press "x" key when CTRL key is hold
+and then press "c" key when CTRL key is hold.
+In commands first "C-" means CTRL key.
+"M-" means Meta key which is usually labeled "alt" or "option".
+
+> NOTE: not all terminals support Meta key.
+But it can be emulated by pressing ESC key and then a target key sequentially.
+For example for command `M-f` you can press "f" while holding "alt" or you can
+type ESC and then press "f".
+
+## Movements
+
+Here is a summary of simple cursor-moving operations,
+including the word and sentence moving commands:
+
+```
+C-f     Move forward a character
+C-b     Move backward a character
+
+M-f     Move forward a word
+M-b     Move backward a word
+
+C-n     Move to next line
+C-p     Move to previous line
+
+C-a     Move to beginning of line
+C-e     Move to end of line
+
+M-a     Move back to beginning of sentence
+M-e     Move forward to end of sentence
+
+M-<     Move to beginning of whole text
+M->     Move to end of whole text
+
+C-l     Position line with cursor at the center of screen.
+        If it is at the center, position at the top.
+        If at the top, position at the bottom.
+        If at bottom then position at the center and so on.
+```
+
+Most of commands be prefixed with `C-u <NUMBER>` for a repeat count.
+But `C-v` and `M-v` take it as amount of lines to scroll. E.g. `C-u 10 C-v`
+will scroll down 4 lines trying to leave cursor in its place.
+
+```
+C-u <NUMBER> <CMD>  Perform <CMD> command <NUMBER> times.
+                    E. g. C-u 5 C-n will move to next line 5 times.
+
+M-<NUMBER> <CMD>    Same as above. Type <NUMBER> when holding Meta.
+```
+
+You can abort current command by `C-g`. If you change your mind after typing
+a part of a command you can abort it by `C-g`. Or you can use it to abort long
+running command.
+
+So if you type `C-u 100 C-g C-f` it would move cursor forward by 1 symbol
+because you cancelled it with `C-g`.
+
+If you type an unsafe command (`C-x C-l` for example) you see a window
+to confirm it. This happened because emacs has "disabled" commands for a noob's
+safety. Press `n` to cancel it and `<SPC>` (space) to confirm.
+
+## Windows
+
+`C-x 1` kill all windows other than 1.
+
+## Editing
+
+Just type text :)
+
+You can give repat count to a symbol to insert it many times:
+Next `<DEL> = backspace`
+
+```
+M-3 i       produces "iii"
+M-3 <DEL>   removes 3 symbols
+```
+
+Delete text as usual with DEL or Backspace keys. Or...
+```
+<DEL>     delete the character before the cursor
+C-d       delete the character under (after) the cursor
+
+M-<DEL>   kill the word before the cursor
+M-d       kill the word after the cursor
+
+C-k       kill to end of line
+M-k       kill to the end of sentence
+```
+
+> The sentence commands assume that you follow the American typist’s
+convention of putting two spaces at the end of a sentence.
+
+```text
+C-<SPC>   Set mark/Start text selection/Visual mode in Vim
+C-w       Kill (cut) selected text
+C-y       Yank (paste) killed text
+M-y       Yank previous kill and replace paste buffer with text killed earlier
+```
+
+In the previous paragraph there were "kill" and "delete" terms. "Kill" is the
+same as "delete" but it copies the text.
+
+To undo latest changes type `C-/` or `C-_` or `C-x u`.
+
+## Files
+
+Current opened file name can be found at the bottom of the screen.
+To open a file type `C-x C-f` and type a file name. To write changes type
+`C-x C-s`.
+
+First time you type `C-x C-s` focus will jump to the bottom screen
+mini-buffer and prompt you a file name to write.
+
+When editing and saving file emacs copies unedited version with the same
+name suffixed by "~" not to lose it.
+
+## Buffers
+
+You can open one file, then another by typing `C-x C-f <FILENAME>` and so on.
+All these files remain open in Emacs and stored in "buffers".
+
+To switch between buffers type `C-x b <BUFFERNAME>`.
+
+Emacs does not save files when you switch current buffer, but you don't have
+to switch to the right buffer to save it - use `C-x s` (save unsaved buffers).
+
+## Commands
+
+