creat(2)                                                 creat(2)



     NAME
          creat - create a new file or rewrite an existing one

     SYNOPSIS
          int creat (path, mode)
          char *path;
          int mode;

     DESCRIPTION
          creat creates a new ordinary file or prepares to rewrite an
          existing file named by the path name pointed to by path.

          If the file exists, the length is truncated to 0 and the
          mode and owner are unchanged.  Otherwise, the file's owner
          ID is set to the effective user ID, of the process the group
          ID of the process is set to the effective group ID, of the
          process and the low-order 12 bits of the file mode are set
          to the value of mode modified as follows:

               All bits set in the process's file mode creation mask
               are cleared.  See umask(2).

               The ``save text image after execution bit'' of the mode
               is cleared.  See chmod(2).

          Upon successful completion, the file descriptor is returned
          and the file is open for writing, even if the mode does not
          permit writing.  The file pointer is set to the beginning of
          the file.  The file descriptor is set to remain open across
          exec system calls.  See fcntl(2).  No process may have more
          than 20 files open simultaneously.

          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.

          The system-scheduling algorithm does not make this a true
          uninterruptible operation, and a race condition may develop
          if creat is done at precisely the same time by two different
          processes.

          creat will fail if one or more of the following are true:

          [ENOTDIR]      A component of the path prefix is not a
                         directory.

          [ENOENT]       A component of the path prefix does not
                         exist.




     Page 1                                        (last mod. 1/14/87)

     creat(2)                                                 creat(2)



          [EACCES]       Search permission is denied on a component of
                         the path prefix.

          [ENOENT]       The path name is null.

          [EACCES]       The file does not exist and the directory in
                         which the file is to be created does not
                         permit writing.

          [EROFS]        The named file resides or would reside on a
                         read-only file system.

          [ETXTBSY]      The file is a pure procedure (shared text)
                         file that is being executed.

                         Note: If you are running an NFS system and
                         you are accessing a shared binary remotely,
                         it is possible that you will not get this
                         errno.

          [EACCES]       The file exists and write permission is
                         denied.

          [EISDIR]       The named file is an existing directory.

          [EMFILE]       Twenty (20) file descriptors are currently
                         open.

          [EFAULT]       path points outside the allocated address
                         space of the process.

          [ENFILE]       The system file table is full.

     RETURN VALUE
          Upon successful completion, a non-negative integer, namely
          the file descriptor, is returned.  Otherwise, a value of -1
          is returned and errno is set to indicate the error.

     SEE ALSO
          chmod(2), close(2), dup(3), fcntl(2), lseek(2), open(2),
          read(2), umask(2), write(2).














     Page 2                                        (last mod. 1/14/87)