man(1) Manual page archive

     CREAT(2)                                                 CREAT(2)

          creat  -  create a new file

          creat(name, mode)
          char *name;

          Creat creates a new file or prepares to rewrite an existing
          file called name, given as the address of a null-terminated
          string.  If the file did not exist, it is given mode mode,
          as modified by the process's mode mask (see umask(2)). Also
          see chmod(2) for the construction of the mode argument.

          If the file did exist, its mode and owner remain unchanged
          but it is truncated to 0 length.

          The file is also opened for writing, and its file descriptor
          is returned.

          The mode given is arbitrary; it need not allow writing.
          This feature is used by programs which deal with temporary
          files of fixed names.  The creation is done with a mode that
          forbids writing.  Then if a second instance of the program
          attempts a creat, an error is returned and the program knows
          that the name is unusable for the moment.

          write(2), close(2), chmod(2), umask (2)

          The value -1 is returned if: a needed directory is not
          searchable; the file does not exist and the directory in
          which it is to be created is not writable; the file does
          exist and is unwritable; the file is a directory; there are
          already too many files open.

          (creat = 8.)
          sys creat; name; mode
          (file descriptor in r0)