What is the easiest way to get the UUID of a hard drive partition programmically in Linux? (Using C)
Use libblkid from the util-linux-ng distribution. It includes some sample code.
(Your system probably already has a "blkid" utility linked against some version of libblkid.)
What Nemo said.
Or... You could open and read the contents of /proc/mounts, and ignore all lines that don't start with /dev/disk/by-uuid/. Slightly more work, but no dependency.
Related
This question may be a little off topic. But I was wondering if there was a way for me to look at the descriptions of C functions using vim or neovim. Is it possible to look at their documentations by doing something like :help? This would really be helpful since I wouldn't need to lookup to my browser everytime.
I am unclear about these things:
Can :help be my friend here ?
Can I use LSPs to do something like this ?
I am using latest Neovim inside Ubunutu 20.04 in WSL. Is this helpful somehow ?
By pressing K, the keyword under the cursor is looked up using a configured keyword lookup program, the default being man. This works pretty much out of the box for the C standard library.
For C++, you might want to look at something like cppman.
Well yes, you can get the description of C functions by using a LSP (language server plugin)! Here is an image of me using clangd as my LSP:
You'd "just" need to install the LSP and start it. I don't know how familiar you're with neovim, but just in case if you don't know how to install a plugin or to be more specifique: If you don't know how you can install a LSP server, then you can do the following:
There're plenty videos how to set up a LSP-Server for your language. Here's an example.
If you don't want to set up on your own, you can pick up one of the preconfigured neovim setups (some of my friends are recommending lunarvim)
But yeah, that's it. If you have any further questions feel free to ask them in the comments.
Happy vimming c(^-^)c
Let's explain how "K" command works in more detail.
You can run external commands by prefixing them with :! command. So running man tool is as easy as
:!man <C-R><C-W>
Here <C-R><C-W> is a special key combination used to put word under cursor from text buffer down to command line.
Same for showing Vim's built-in help page
:help <C-R><C-W>
As it feels tedious to type that, Vim also defines K Normal mode command that does pretty much the same thing. Except the tool name is taken from value of an option named "keywordprg".
So doing set keywordprg=man (default for *nix systems) makes K to invoke !man tool; while set keywordprg=:help is for bultin help.
Also, the option :h 'keywordprg' is made global or local-to-buffer, so any Vim buffer is able to overwrite global setting. For example, this is already done by standard runtime for "vim" and "help" buffers, so they call ":help" instead of "man".
The problem with :!man command is that it shows "black console". It'd be nice if we could capture man's output and open it inside Vim just like a builtin help page. Then we could also apply some pretty highlighting, assign key macros and all such. This is a pretty common trick and it is already done by a standard plugin shipped with Vim/Neovim.
A command that the plugin provides is called :Man, so you can open :Man man instead of :!man man, for example. The plugin is preactivated in Neovim; for Vim you still need to source one file manually. So to make use of this plugin you'll need something like this
set keywordprg=:Man
if !has("nvim")
source $VIMRUNTIME/ftplugin/man.vim
endif
The previous answer recommending cppman is the way to go. There is no need to install a bulky language server just for the purpose of having the hover functionality. However, make sure you're caching the man pages via cppman -c. Otherwise, there will be a noticeable delay since cppman is fetching the page from cppreference.com on the fly.
If you like popups for displaying documentation, convert the uncompressed man pages (groff -t -e -mandoc -Tascii <man-page> | col -bx), and set keywordprg to your own wrapper to search for keywords according to your needs.
I am trying to navigate and understand whoami (and other coreutils) all the way down to the lowest level source code, just as an exercise.
My dive so far:
Where is the actual binary?
which whoami
/usr/bin/whoami
Where is it maintained?
http://www.gnu.org/software/coreutils/coreutils.html
How do I get source?
git clone git://git.sv.gnu.org/coreutils
Where is whoami source code within the repository?
# find . | grep whoami
./man/whoami.x
./man/whoami.1
./src/whoami.c
./src/whoami
./src/whoami.o
./src/.deps/src_libsinglebin_whoami_a-whoami.Po
./src/.deps/whoami.Po
relevant line (84):
uid = geteuid ();
This is approximately where my rabbit hole stops. geteuid() is mentioned in gnulib/lib/euidaccess.c, but not explicitly defined AFAICT. It's also referenced in /usr/local/unistd.h as extern but there's no heavy lifting related to grabbing a uid that I can see.
I got here by mostly grepping for geteuid within known system headers and includes as I'm having trouble backtracing its definition.
Question: How can I dive down further and explore the source code of geteuid()? What is the most efficient way to explore this codebase quickly without grepping around?
I'm on Ubuntu server 15.04 using Vim and some ctags (which hasn't been very helpful for navigating existing system headers). I'm a terrible developer and this is my method of learning, though I can't get through this roadblock.
Normally you should read the documentation for geteuid. You can either read GNU documentation, the specification from the Open Group or consult the man page.
If that doesn't help you could install the debug symbols for the c-library (it's called libc6-dbg or something similar) and download the source code for libc6) then you point out the path to the source file when you step into the library.
In this case I don't think this would take you much further, what probably happens in geteuid is that it simply issues an actual syscall and then it's into kernel space. You cannot debug that (kernel) code in the same way as you would debug a normal program.
So in your case you should better consult the documentation and read it carefully and try to figure out why geteuid doesn't return what you expect. Probably this will lead to you changing your expectation of what geteuid should return to match what's actually returned.
I'm trying to remove a file in a C program, but when I use the remove() function it completely removes the file and not sending it to the trash. How can I remove a file to trash?
Thanks in advance!
On Mac OS, you should use the recycleURLs:completionHandler: method in NSWorkspace.
Almost every operating system provides an API to perform a soft delete by moving files to the trash. Unfortunately there is no unified specification on how a trash / recycling bin should work. On Windows you can use IFileOperation, macOS has the NSFileManager and on Linux and BSD you either use a tool that implements the FreeDesktop.org trash specification such as gio trash (GNOME), kioclient5 move (KDE), trash-cli or implement your own.
Another solution is using a cross-platform library that allows to move files and directories to the trash / recycling bin like libtrashcan. This simplifies development because you only use a single function call without worrying about platform specific details.
For Windows See SHFileOperation with FOF_ALLOWUNDO.
http://msdn.microsoft.com/en-us/library/bb762164.aspx
On Mac OS X, you have to call FSMoveObjectToTrashSync (or its async friend) from CoreServices.
In linux i will do...
system("mv your_file.txt /home/username/.local/share/Trash/");
If you are on Windows try this.
Open a Command Prompt (DOS windows) and type
cd \$RECYCLE.BIN
dir \a
and you will get a list of all the trashes of all the users in your computer.
In your program move the file to the proper trash.
I have a huge project, whole written in C language and I have a single make file that is used to compile it. The project C files contains lots of capitalize problems in it's header files, meaning there are tones of header files that were miss-spelled in lots of C files.
The problem is I need to migrate this project to compile on Linux machine and since Linux is case sensitive I got tones of errors.
Is there an elegant way which I can run make file in Linux and tell him to ignore case sensitive?
Any other solution will be welcome as well.
Thanks a lot.
Motti.
You'll have to fix everything by hand and rename every file or fix every place with #include. Even if you have a huge project (comparable with linux kernel), it should be possible to do this during a hour or two. Automation may be possible, but manual way should be better - because script won't be able to guess which name is right - filename, or the name used in #include.
Besides, this situation is a fault of original project developer. If he/she wasn't sloppy and named every header in every #include correctly, this wouldn't happen. Technically, this is a code problem similar to syntax error. The only right way to deal with it is to fix it.
I think it takes not too long to write a small script, which goes thru the directories first, then replaces C headers. Explained:
Scan the headers' folder and collect filenames.
Make a lowercase list of them. You have now original and locased pairs.
Scan the C source files and find each line contains "#include"
Lowercase it.
Find the lowercase filename in the list collected and lowercased from headers.
Replace the source line with the one collected from headers.
You should put the modified files into a separate folder structure, avoid overwriting the whole source with some buggy stuff. Don't forget to create target folders during the source tree scan.
I recommend a script language for that task, I prefer PHP, but just it's the only server-side script language which I know. Yep, it will run for a while, but only once.
(I bet that you will have other difficulties with that project, this problem is not a typical indicator of high quality work.)
Well I can only tell you that you need to change the case of those header files. I don't know that there is any way you can make it automatic but still you can use cscope to do it in a easier way.
http://www.linux-tutorial.info/modules.php?name=ManPage&sec=1&manpage=cscope
You can mount the files on a case-insensitive file system. FAT comes to mind. ntfs-3g does not appear to support this.
I use the find all and replace all functionality of Source Insight when i have to do complete replacement. But your problem seems quite big, but you can try the option to replace every header file name in all occurences of source files using the
"Find All" + "Replace" functionality. You can use notepad++ too for doing the same.
A long time ago there was a great tool under MPW (Macintosh Programmer's Workshop) called Canon. It was used to canonize text files, i.e. make all symbols found in a given refernce list have have the same usage of upper/lower case. This tool would be ideal for a task like this - I wonder if anything similar exists under Linux ?
Is there any .obj to .cpp converter?
Is it possible to do it?
MICROSOFT VISUAL STUDIO auto-magically deleted my code files when pressed the F5 key.
Please help me.
I have the .obj files (VS forgot to delete them.ha ha ha).
Unfortunately it is impossible to decompile an .obj file back to source. More info here.
shut down your computer, boot from removable media, some sort of the UNIX, and run strings utility on your hard drive. It may be able to recover text off your source code.
As everyone has pointed out, this is impossible.
I would suggest that before you rebuild all those files, you take the time to look into SVN or another version control system.
Version Control allows you to save copies of your files to a safe place. If the compiler eats your homework, you can update with the last copy you saved to the repository.
You should try Recuva
You are out of luck. There is no safe way to reverse an obj file back to its cpp source.
I do not think that is actually possible. You'd be reversing the compilation process, which from my knowledge is not possible.
NO, it's not possible. obj files contain object code, not source code. The compilation process is typically not reversible.
PS: Visual Studio did surely not delete your code files when you pressed F5. They are somewhere, or you've deleted them accidentially.
It is impossible to do that...as all the code's comments and variables are translated into a machine code, you cannot deterministically reproduce a variable name by gleaning in on assembler byte code, Consider this as an example of a mock dump of a binary image:
0x55 0x90 0x33 0xf0 ....
Now, how can you tell that's variable foobar that is of type int....
Hope this helps,
Best regards,
Tom.
As said earlier, it is impossible to get the C source code from on obj. As an alternative, you can try a file recovery utility and scan your disk for lost files. I have previously used testdisk with partial success.
Also, you really need to use some form of SCM!
.obj files are text files for a 3d model I was actually looking for something to bring them into C++ to display using OpenGL. there are programs out there to load them into C++ I was looking for one to download when I came across this.
en.wikipedia.org/wiki/Obj