C如何防止文件被覆盖

Question

Currently the the file gets created and overwritten. I am trying to get it so that if the file already exists it just exits the program. open must be used.

if ((dest = open(argv[2], O_WRONLY | O_CREAT, 0644)) == -1) {
    printf("Error File %s exists", argv[2]);
    return 3; 
 }

Answer 1

Just use O_EXCL :

O_EXCL Ensure that this call creates the file: if this flag is specified in conjunction with O_CREAT , and pathname already exists, then open() will fail .