File Creation in C Programming Quiz

File Creation System Calls

• The open() system call is utilized for creating files in a Unix-like operating system.

Flags for Creating a File

• O_CREAT flag is used with open() to create a new file if it does not already exist.
• O_WRONLY flag allows the file to be opened for writing only, restricting read access.
• To ensure a file is writable exclusively, combining O_CREAT and O_WRONLY is essential.

O_TRUNC Flag Functionality

• The O_TRUNC flag, when used with open(), truncates an existing file to zero length upon opening, effectively deleting its contents.

Example Code Explanation

• The code int fd = open("foo", O_CREAT|O_WRONLY|O_TRUNC, S_IRUSR|S_IWUSR); creates a new file named "foo".
• If "foo" already exists, its contents will be truncated due to the O_TRUNC flag.
• The file is created with permissions allowing the owner to read and write (S_IRUSR and S_IWUSR).

Third Parameter of open() System Call

• The third parameter, typically the mode, specifies the file permissions when a new file is created.
• It dictates the access rights for the file owner, group, and others, in this case allowing read and write for the user only.