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@(#)creat.2 4.1 (Berkeley) 05/09/85

C 4 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)

A file cannot be truncated while any process has pages set up by a vread on that file which have not been referenced.