Emacs bookmark and accessing across different local path - emacs

When I bookmark a File in emacs, it has the full-path C:/WindowPath/CommanPath/File I can access the same directory from Linux with /LinuxPath/CommanPath/File. But, when I try to bookmark in one OS and access in other OS, the file-path are different and I cannot access the same file from M-x list-bookmark interface. How I can resolve this? Please note that the 'CommanPath' is same for both OS.
Is there something in bookmark library that I can use? If that is not the case, then how should I create shortcuts so it can work seamlessly in both OS, or for that matter in any path ?
Thanks.

Hm. How does Emacs find the same file starting with different absolute file names on different OS's? If you can track that down then you can likely make the bookmark code do the same thing. The bookmark just saves the absolute file name in the form of the OS you were using at the time you created the bookmark. Giving that to Emacs to find should be no different from giving it to find-file, which you say works.
(That is, I think that's what you're saying: you can type the Windows form of the file name at C-x C-f when on Linux and it just works, and vice versa.)
The basic file-finding function is find-file-noselect, but all it seems to do in this regard is (abbreviate-file-name (expand-file-name FILENAME)), which would not be sufficient if given FILENAME as an absolute name from the wrong file system.
If you cannot figure out how to code this generally, you might be able to use directory-abbrev-alist to make your own explicit correspondence between the two directory prefixes. Dunno.
Interesting question.

Related

purpose of ~/.emacs.d/auto-save-list/

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.

Emacs what is the file structure of aspell personal dictionary

I like to keep my Emacs init.el file under version control/synced to the web so I can pull it down from multiple computers. I have just started using M-x ispell (which confusingly I'm pretty sure is invoking aspell, whatever the difference) to check my spelling and have begun adding to my personal dictionary of words that should not be recognized as errors. How do I now use this dictionary on another computer? I guess I can break the question up:
What files does aspell generate on my machine that pertain to my personal dictionary and what of these files will I need to keep under version control to use on another machine?
If I simply copy them to the same directory structure on another machine (potentially different OS) should I expect it to magically recognize my personal dictionary words?
If the answer to 2. is "No", what do I need to do/configure to tell aspell "hey, this is my personal dictionary file(s) you should be checking against"?
Here's my config:
(setq ispell-personal-dictionary (concat emacs.d "ispell_dict"))
emacs.d is a string that stores site-lisp directory. On my current machine
it's "~/Dropbox/source/site-lisp/".
As long as a set it up properly on different machines, the dictionary will sync.

Emacs and cscope with multiple directories

How do I set up cscope in Emacs when my source code lives in multiple directories?
Say I have several paths for my C++ project:
/path/to/my/code (and subdirectories)
/path/to/other/code (and subdirectories)
/path/to/static/linking/include/files (and subdirectories)
/path/to/static/linking/lib/files' (and subdirectories)
I would like to use xcscope to navigate/look up symbols in my code and the library that I am linking to.
The instructions for xcscope.el say that I should first run C-c s (Cscope->Create list and index) at /path/to/my/code, but I am then confused about how I to have the other paths indexed by cscope.
The documentation says I should go to the other directories and run cscope -b, but what I am supposed to do after that?
I looked at the cscope.files file that C-c s built. I think I am supposed to add my other paths to this file, but this file includes a list of source code files (not directories).
Do I have to manually edit cscope.files to add every single file that I want to index that is outside of my project's root directory?
The documentation is confusing.
I got one sol'n from http://cscope.sourceforge.net/large_projects.html. Still confusing.
cscope.files is aptly named. It is NOT directories. It is files, only files. Which is as daunting as it sounds. What if you have hundreds of files. Then you have to write hundreds of lines, one per file, into cscope.files. No joke.
Automate it with some scripting. E.g., on linux, use bash scripts and redirection (>,>>,|) operators to select and filter files from any and all directories into that cscope.files.
What about the directory where cscope.files resides? IF you don't include those files, it'll only find them when you open your project (in emacs, but probably applicable to any IDE) in that source directory. So, include them, too, for easy opening of your project from anywhere.
The option "recursive/-R" seems obvious to send to cscope-indexer. Nope, not with many root directories. Does nothing (probably could do something with scripts or elisp or who knows). Just feed those files, absolute path, into cscope.files. And you might have to make sure you have only one cscope.files per project. Don't split them up relative to each diretory. Or maybe you can, something to look into.
Remember, include the /path/to/each/file/ before the file if you want cscope.files to point to it from anywhere. cscope isn't "smart", it's dumb, it just takes directions for where to look and it won't know where to look for "filename", without knowing where it is. You're just asking it to call locate filename, which it can't do anyway, when you give it a lonely filename without a dir path outside of the directory that a particular cscope.files resides.
I hope there's a way to use xcscope inside emacs, just adding directories which it will catalog and index, as the xcscope docs and emacs menu suggest. But I didn't succeed in making it work that way.
Wouldn't a soft link (ln -s) work? Worked for me.

How can I identify the owner/creator of a Buffer in Emacs

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

How to write .emacs from Emacs when I've deleted .emacs

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.