How to check if a file exists before creating a new file

Question

I want to input some contents to a file, but I\'d like to check first if a file with the name I wish to create exists. If so, I don\'t want to create any file, even if the f

Answer 1

Looked around a bit, and the only thing I find is using the open system call. It is the only function I found that allows you to create a file in a way that will fail if it already exists

#include 
#include 

int fd=open(filename, O_WRONLY | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
if (fd < 0) {
  /* file exists or otherwise uncreatable
     you might want to check errno*/
}else {
  /* File is open to writing */
}

Note that you have to give permissions since you are creating a file.

This also removes any race conditions there might be