Writes the characters given by string to the file given by fileId. FileId must have been the return value from a previous call to open, or it may be stdout or stderr to refer to one of the standard I/O channels; it must refer to a file that was opened for writing. If no fileId is specified then it defaults to stdout. Puts normally outputs a newline character after string, but this feature may be suppressed by specifying the -nonewline switch. Output to files is buffered internally by Tcl; the flush command may be used to force buffered characters to be output.