How to temporary select and edit some lines in a buffer? - emacs

I'm stuck on this problem. I have a file with almost 10k lines. Some of them should be deleted and I can get an hint from their content, e.g. if they contains a certain pattern "xyz", maybe they must be deleted. So, my idea is to:
* select only those lines containing each pattern in my list
* manually inspect them and change the ones actually to be deleted prepending them a "--" (or similar)
* ...and at the very end, delete all the lines starting with "--".
As keep-lines actually delete all the un-kept lines (TIL), is there any other way to do what I need? Thanks in advance.

One idea would be to use M-x occur to select possible candidates. Then, use "e" in the Occur buffer to enter "Occur Edit Mode". In this mode, edits in the Occur buffer are reflected into the originating buffer. So maybe you can just delete lines there altogether.

You might like to try M-x all. It's like M-x occur except that buffer changes get propagated to the original buffer. all can be installed from GNU ELPA (i.e. via M-x list-packages).

It sounds like you could do this with query-replace-regexp.
M-C-% (or M-x query-replace-regexp)
Enter ^.*xyz.*$ as your search term and leave the replace term blank (hit enter)
Inspect each matching line in turn, hit space to delete or n to leave. Make sure you start at the beginning of the buffer to catch everything.

You can get hide-lines and use M-x hine-lines-not-matching. Since it's still the same buffer (just displayed differently), you can edit the visible lines as you wish.

Related

Emacs multiple-cursor - Cut and yank in multiple lines

Using the 'multiple-cursor' emacs package,
when I mark a word and cut ('C-w') in different multiple cursors, the only word in the 'active' cursor I control is cut.
I want to select different words in multiple positions and yank it to other relative position.
When I first tried this I remember some yes or no option at the screen bottom, but I couldn't really notice this at first and some keystroke made it to "no". I guess this might have been an option for multiple-cut. But I don't know how to revert this choice.
How do you do multiple cut and yank in emacs?
This works by default, so at some point you have indeed asked the library not do do this.
These settings are stored (by default) in ~/.emacs.d/.mc-lists.el
Just edit that file appropriately, and then M-x eval-buffer RET to make those same changes in the running instance.

Is there a way to make regions in term modes respect line wrapping?

When using a term mode derivative (like ansi-term or multi-term), I often want to select a region and copy it someplace else. If that region includes a line which wraps at the edge of the terminal window, pasting that region in another buffer always inserts a hard newline at the place where term wrapped the line. This means I often have to go back and clean up pasted text. Is there a way to avoid doing this? I tried both term-line-mode and term-char-mode; both do the same thing.
I do not want to write a yank hook which strips out all newlines, since I want to preserve existing hard newlines in the original content.
This works for me:
(setq term-suppress-hard-newline t)

How to edit multiple strings in emacs at sametime?

I want edit multiple strings at once by selection the list of strings needs to edit. After selection, when I type, it should modify all the text in the selected strings.
How to achieve multiple string edit?
I really like iedit.el, which highlights all the occurrences of the string, and shows you the modifications as you make them.
replace-string or query-replace quoth the Emacs manual.
You want "all.el" by Per Abrahamsen:
Just like occur, except that changes in the All buffer is
propagated to the original buffer.
Essentially you say
M-x all RET pattern RET
then edit the matching occurrences in All. Changes made in that buffer are propagated back into the original buffer.
I personally find this much more convenient than iedit, but YMMV.
It's hard to track down the source code for all.el, so I pasted it here.

Multiline sentence in emacs

If I have a multiline sentence in Emacs it naturally overflows onto the the following lines. Now, if my cursor is at the beginning of such a sentence and I press the DOWN ARROW key, the cursor is placed at the beginning of the next sentence (which might be at 4-5 lines down), rather than on the next line itself (which other editors do). Same is the behavior of the END and HOME keys.
Is there a way in which I can change this behavior and get the cursor on the next line instead of the next sentence?
I haven't yet tried it myself, but I think what you are asking for is the default behavior for emacs 23. What version are you running?
You might want to check out the page Move By Visible Lines page on the emacswiki.
You might want to try auto-fill-mode or longlines-mode. To get either use M-X then type the command you want. Toggle them off the same way.
If that doesn't work you may want to examine the binding that is being applied to your down arrow. Type C-h k then hit the down arrow key.
It sounds as though the text is wrapping, so by definition (a line being a group of characters separated by a carriage return), it is moving down to the next line.
I agree it is a pain, however a lot of other editors also have this behaviour.
One way is to turn off wrapping:
M-x toggle-truncate-lines
You wont be able to see all of the text in the editor, however it will move down to the next line.

Highlight buffer modifications

It often occurs that a file buffer is modified (duh!). Before exiting, emacs asks whether to save the changes. Now it would be interesting to know what actually changed. Is there a way to find out?
As of Emacs 22.1 (at least), 'save-buffers-kill-emacs (the default binding for C-x C-c) prompts you for each unsaved buffer that has a file. Type a d when prompted to save and see the diff.
From the help documentation:
Save some modified file-visiting buffers. Asks user about each one.
You can answer `y' to save, `n' not to save, `C-r' to look at the
buffer in question with `view-buffer' before deciding or `d' to
view the differences using `diff-buffer-with-file'.
If you look at the prompt, it should say something like:
Save file /path/to/file.txt? (y, n, !, ., q, C-r, d, or C-h)
Typing C-h gives you a little more verbose description (but d is what you are asking for):
Type SPC or `y' to save the current buffer;
DEL or `n' to skip the current buffer;
RET or `q' to give up on the save (skip all remaining buffers);
C-g to quit (cancel the whole command);
! to save all remaining buffers;
C-r to view this buffer;
d to view changes in this buffer;
or . (period) to save the current buffer and exit.
I use diff-buffer-with-file, and select the file that the buffer came from (which is the default anyway for the command... just hit enter).
You can also use highlight-changes-mode, though this won't track changes until you turn it on, so not so useful if you want to see what changed when you're closing a file that has not been in this mode :-)
You can have highlight-changes-mode enabled. It will display all changes in red. However it won't show you whitespace changes and will mark removals only with an red _. See also http://www.emacswiki.org/emacs/TrackChanges.
I found this post about tracking changes by djcb most helpful regarding tracking changes in Emacs. The trick is to add the following to your .emacs:
;; higlight changes in documents
(global-highlight-changes-mode t)
(setq highlight-changes-visibility-initial-state nil); initially hide
and then toggle highlight-changes-visible-mode when you want to see what has changed.
In this case I type undo to see the last change (usually some stray character which got typed in the wrong window, since I save early and often).
It would be nice if there were some other indication of the current changes, e.g. in the border like quick diff in Eclipse text editors.
I use goto-chg for things like that. It's not perfect, but it always is enough to jog my memory about what change I made and promptly forgot about.