fconfigure - Set and get options on a channel
fconfigure channelId fconfigure channelId name fconfigure channelId name value ?name value ...?
TCL core command
The fconfigure command sets and retrieves options for channels.
http://www.tcl.tk/man/tcl8.5/TclCmd/fconfigure.htm
Instruct Tcl to always send output to stdout immediately, whether or not it is to a terminal:
fconfigure stdout -buffering none
Instruct Tcl to read pure bytes from a channel and write bytes to it, rather than characters:
fconfigure $binaryDataFile -translation binary