I am currently trying to compile and link a 32 bit application on my Debian 64 bit, but it fails at link time. The command I’m using (in my Makefile) to compile is: This seems to work. Then I link with the following command: This fails and gives the following errors: What I’ve tried so far (usual …
A simple C++ shared memory program written on linux: segmentation fault
I got the code from a tutorial on shared memory. It worked until I defined struct LOCK and tried to write LOCKs instead of char* into the shared memory. Could someone please help me figure out the problem here that causes the segmentation fault? Answer You are placing vectors and strings into shared memory. B…
Concatenating Files And Insert New Line In Between Files
I have multiple files which I want to concat with cat. Let’s say I want to concat so that the final file looks like: Instead of this with usual cat File*.txt > finalfile.txt What’s the right way to do it? Answer You can do: Make sure the file finalfile.txt does not exist before you run the abov…
Is malloc deterministic?
Is malloc deterministic? Say If I have a forked process, that is, a replica of another process, and at some point both of them call the malloc function. Would the address allocated be the same in both processes? Assuming that other parts of execution are also deterministic. Note: Here, I’m only talking …
Why makecontext does not work with pthreads
From makecontext() manual… Due to limitations in the current pthread implementation, makecontext should not be used in programs which link against the pthread(3) library (whether threads are used or not). Now my question is, why it doesn’t work and what are the alternative methods. Actually I̵…
Bash: executing commands from within a chroot and switch user
Im writing a script that should do this… I have tried this approach: This tries to execute the user switching and the script as a string command to bash…however what it does, is it “stops” after “su -” and doesnt execute the script. However, once I leave the “su -R…
what script (like .bat) would run on windows, mac, and linux
I have a bat script that I’d like to make work on windows/Mac/linux, but I read .bat is only for windows. How can I make this script work on Mac and linux, or what type of script can I write that would work on all 3. Answer If you don’t want to step up to a language like C, I
Turn on core/crash dumps programmatically
I know I can run “ulimit -c unlimited” In the shell to turn on core dumps for the current user. What I am wondering is how can I do this programmatically from C? I see there is a ulimit call, but it’s been deprecated in favour of get/setrlimit. What I want to know is what is the equivalent c…
Version control system which keeps track of individual files
Up to now I used git to manage my latex-files. However git manages all latex-files in a folder at once. What I want is a version control system which gives me a history for each file separately lets me checkout old versions of individual files without affecting the other ones lets me make branches for each in…
undefined reference to sync_fetch_and_add_4
Whenever I try to use __sync_fetch_and_add with -m32 on a 64 bit machine, I get the following error, while it compiles fine with normal 64 bit. I am using gcc compiler 4.1.2. What can be the problem here and what is the solution? Answer Using -march=i486 flag did the trick for me.