I have Emacs open but accidentally I've deleted the .emacs file it read when it started. This represents about 15 years of tweaking. (I know, I know, backups.)
Is there a way to get Emacs to write out the .emacs file I've deleted?
I wouldn't normally ask such a lame question on SO but I know I only have a day or so before this Emacs session ends.
As ayckoster suggests, you might try a file recovery or forensics tool like The Sleuth Kit. Or, and this may seem crazy, if you're on a Unix-like system, you could search through the raw disk device (on the Mac I'm currently on, that would be /dev/rdisk1). Seriously, several times I've been too lazy to break out a full-blown recovery tool but instead used something like sudo less -f /dev/rdisk1, searched for a string I knew was in the file (global-set-key, anyone?), and succeeded in recovering the file's original content.
If you have Emacs' backup feature turned on, you should have a copy of your next-to-last .emacs file in ~/.emacs~. If so, just rename that one to ".emacs" and you will have the .emacs file with all but your latest changes. Even if you don't currently have backups enabled, you might still have a substantial chunk of your .emacs file in the last backup on file. You should also look at the value of the variable "backup-directory-alist" - it specifies location(s) for backup files to be stored if the default (same directory as modified file) isn't used.
Otherwise, how good is your memory... ;-)
EDIT: Since you don't have a backup of your .emacs file but you have a running Emacs instance that was started with that .emacs file, another thing you can do is to save all the custom settings that would have been defined in your .emacs file. To do this, do something like:
(setq custom-file "/my/home/directory/.emacs-custom.el")
(custom-save-all)
Then, you could create a new .emacs file and add the following lines to it:
(setq custom-file "/my/home/directory/.emacs-custom.el")
(load custom-file)
That will at least restore some of the custom variable settings that were in your .emacs file.
Emacs evaluates your .emacs file and afterwards it is closed. So basically you cannot get your .emacs back.
A solution might be to use a file recovery application. The odds of your .emacs being on your hard drive are quite good.
As most such programs cannot deduce the file name or directory name of the deleted file you have to know the content of your .emacs.
Then you can restore all currently deleted files in some folder and recursively search for the contents of your .emacs.
This process might take very long. You have to decide if its worth your effort.
I don't know of any way to get Emacs to provide the original .emacs file, but you can certainly interrogate the loaded function and variable symbols, and obtain their values.
This would be rather a lot of work, but I think in theory you should be able to obtain a good chunk of this data in some form or other, if you succeeded in filtering it all down to what you knew was yours.
For evaluated functions, (symbol-function 'SYMBOL) will return a (less-readable) definition of the supplied function. You could then use (fset 'SYMBOL VALUE), where VALUE is the result of the call to symbol-function, to define that function in a new .emacs file. That would give you an approach for recovering your defined functions.
http://www.gnu.org/s/emacs/manual/html_node/elisp/Function-Cells.html
http://www.gnu.org/s/emacs/manual/html_node/elisp/Symbol-Components.html
You might also look at:
How to print all the defined variables in emacs?
This is a very incomplete starter, but given time constraints I'm posting and marking it community wiki, if anyone wants to run with it.
A how-to for dumping the state of the application in a reliably restorable fashion would be a great start, if the current session is definitely going to be killed (or even if it's not, actually, to guard against crashing or other mishap).
You could potentially re-tag this with some more general data-recovery type tags, to expand the audience.
Related
A directory titled auto-save-list appeared in my .emacs.d folder. In my init.el file, I did not explicitly mention I want this folder to be made. What is the purpose of this folder? I noticed it seems to always be empty: files being auto-saved (starting with #) appear wherever the original file being edited is, not in the auto-save-list directory.
If you search the manual or its index for auto-save-list you will find:
Emacs records information about interrupted sessions in files named
‘.saves-PID-HOSTNAME’ in the directory ‘~/.emacs.d/auto-save-list/’.
This directory is determined by the variable
‘auto-save-list-file-prefix’. If you set ‘auto-save-list-file-prefix’
to ‘nil’, sessions are not recorded for recovery.
– C-hig (emacs)Recover RET
I did not explicitly mention I want this folder to be made.
Emacs and elisp libraries in general write to ~/.emacs.d/ when they need to save data. That's one of the purposes of this directory -- to provide a common place for such files to be written to; and this typically happens without asking explicit permission (although it's also pretty common for you to be able to customize the filename in question if you so wish).
phils already answered the specific question, but to answer the more general question of what to do about miscellaneous files automatically created by Emacs, check out the no-littering package.
Auto save files (the ones with '#') are not handled by no-littering, but the readme gives a work around for those if you wish.
Background:
I modularised the init.el file into several files and tried to load them one by one from init.el.
Each file has a:
(provide 'xxx)
at the end and I use:
(require 'xxx)
to load them.
(before I used load-library to load them, but recent I learned the require command will only load them if they are not loaded.)
Then some wired behaviour appears.
I'm not sure if this is the problem of not loading the library in the right order or of not loading certain file.
So the question is:
How can I see which file are loaded by the require command? (In the 'Message' buffer, I can see files loaded by 'load-libarry', but not by 'require')
You might inspect the variable load-history.
You could look at featurep function and features variable: each time a provide statement is encountered, the features variable is updated.
I have files in some location:
location_a/doc.tex
location_a/doc.cls
...
I want to work on them in another directory via symbolic links:
work_directory/doc.tex -> location_a/doc.tex
work_directory/doc.cls -> location_a/doc.cls
work_directory/doc.pdf
work_directory/doc.log
...
However, when I run emacs doc.tex in the work directory and do some editing, emacs creates a backup file at location_a/doc.tex~. I want the backup file to be stored in the work directory, though. I don't want any new files created in location_a.
How can I make emacs do that?
This is trickier than it seems it should be because backup-buffer insists on chasing the links of the buffer file name before calling any backup file name construction machinery, such as make-backup-file-name-function. The result is that Emacs allows no way to customize this behavior, short of redefining backup-buffer, which is a fairly complicated piece of code.
A compromise solution I came up with is to install an "advice" around backup-buffer that temporarily disables file-chase-links while backup-buffer is being evaluated. This allows the backup file to be in the directory where the symlink resides. However, it also causes Emacs to create the backup by renaming the original symlink, leaving one with work_directory/doc.tex~ being a symlink that points to location_a/doc.tex! Fortunately, this is easy to prevent by setting backup-by-copying to t.
Here is the code. A word of warning: while I have tried it to verify that it works, I cannot guarantee that it will not have an undesirable side effect, like the above interference with the backup mechanism that required backup-by-copying. However, it might also work just fine - just be careful when using it.
(require 'cl) ; for flet
(defadvice backup-buffer (around disable-chase-links)
(flet ((file-chase-links (file) file))
ad-do-it))
(ad-activate 'backup-buffer)
For the fun of it, let me describe a radically different approach, based on directory variables.
In short, you would put in your work-directory/ a file named .dir-locals.el containing:
((nil . ((eval . (set (make-local-variable 'backup-directory-alist)
(list (cons "."
(file-relative-name
(file-name-directory (buffer-file-name))
(file-name-directory (file-truename
(buffer-file-name)))))))))))
What this does is abusing somewhat the backup-directory-alist, and install a local version
of it for all your files in work-directory/. That local version will in turn make sure that any backup file is kept within work-directory.
In order to achieve that, we need 2 things:
have something like '(("." . "path/to/work-directory/")) as the local value
make sure this path is relative to location_a/
The reason for the second point is that as noted elsewhere, the starting point of backup-buffer is indeed the location of the actual file, once symlinks are resolved. And we can't simply put the absolute path without having backup files changing shape (in case of absolute path for the backup directory, the backup filenames encode the complete path, so that there is no collision)
Notes:
you'll need to make sure that specific local variable is recorded in the safe-local-variable-values. Since it's a generic form, it's a one time job though (just hit "!" the first time you're asked about it)
this assumes find-file-visit-truename is set to nil, but I guess you wouldn't ask that question if that was not the case :)
Pros of the approach:
no need for advice (which is always a good thing)
reasonably portable although it assumes your Emacs supports directory variables
you keep the flexibility to put that in place only where you need it
Cons of the approach:
well, obviously you might have to copy that .dir-locals.el in several places
Also note that if you wanted a one-shot approach, you could make it much simpler, such as:
((nil . ((backup-directory-alist (("." . "../path/to/work-directory"))))))
where you actually compute the relative name yourself, once and for all.
How can I check the identity of someone who has created a buffer in Emacs and then later on check whether is the same user accessing that buffer? I mean something like "Who Am I?" in Unix command.. and then check if the same user is accessing that document? --> I want a function or a way to this in my own code
Note the difference between a buffer and a file: A file is something that sits on your hard disk, such as a .jpg image file or a .mp3 aufio file or a .txt file. Some of those files - typically text files - you might want to edit with Emacs. To do so, you can load the file into Emacs - this is called "visiting" a file in Emacs lingo. The contents of the file are displayed in a buffer. But note that you could also have a buffer that is not associated with a file at all - for instance the *scratch* buffer that gets displayed if you start up Emacs without specifying a file.
Thus files and buffers are pretty much orthogonal concepts, although often times you create buffers by visiting a file, and you save the contents of a buffer by writing to a file. (You can create a buffer that is not associated with a file by typing C-x b buffer-name where buffer-name is an identifier not used by any of the already existing buffers.)
A buffer exists only inside a running Emacs. This is why the comments and answers you have gotten so far may not have been what you're looking for: the notion of the creator/owner of the buffer is confusing, because it is obviously the person who's sitting at the keyboard at that particular moment.
Speaking of the owner/creator of a file makes much more sense. In a multi-account setup, more than one user can write to the same disk, and so they might have access to the same files. Now it can be interesting to know who has access, and in particular who owns the file or when it was last modified. In Elisp, you can use the function
(file-attributes FILENAME &optional ID-FORMAT)
to get a list of attributes associated with the file. If your current buffer is visiting a file at all, you can combine that function with the function
(buffer-file-name &optional BUFFER)
which returns the file the buffer is visiting. For a buffer that is not visiting a file, this function returns nil.
Note, however, that some information you might be interested in is not available through (file-attributes ...), such as who last accessed the file and/or who last modified it. This is not so much Emacs' fault, but comes from the fact that the operating system does not store such information.
Also note that the current owner of a file might not necessarily be the person who created it as someone with the required privileges can chown a file after its creation.
To receive information about the current user in the sense of whoami, you can check out the variables
user-login-name
user-real-login-name
user-full-name
by typing C-h v variable-name.
AFAIK seen from system, Emacs is a single process, owned by the user who started it
(getenv "USER")
is the respective to
echo $USER
I know you can navigate the contents of an archive with emacs. Is there a way you can edit those files in place and write the archive transparently?. Currently, I navigate into the archive, write the file to a temp directory, and the use the java jar command to add the file back into the archive. Its a little bit of pain.
P.S. I know there are few use cases where you'd want to do this, but I've inherited a platform that I can't readily modify where I have to cope with this limitation in the short term.
Yes, it just works. Did you try it?
I grabbed a jar file that contained a text file and some java code that would print it out. I edited the txt file within the .jar and saved the text file. It did exactly what I would expect.
EDIT- When saving the archive make sure you use C-x C-s
In emacs-23.2 (not 23.1 or 23.3) this doesn't "just work" on Windows due to a bug. Instead it just writes caution: filename not matched: "<internal path>.
One solution is to simply upgrade to 23.3.
To fix the bug in emacs-23.2, open $EMACS_HOME/lisp/arc-mode.el and replace:
(if (equal (car archive-zip-extract) "unzip")
(shell-quote-argument name)
name)
with:
name
and recompile:
M-x byte-compile-file $EMACS_HOME/lisp/arc-mode.el
This answer comes from the original emacs bug report.