Creating files safely

Enter sysopen
Allows you to list mode explicitly at create time.
Allows you to use explicit options.
Options can avoid need for test at all.


sysopen( FILEHANDLE, $file, O_RDWR | O_CREAT | O_EXCL, 0600 )
    or die;

Operations such as this are called atomic functions
No interfering processing can occur on the machine between the time the system call starts and it completes.