tell(3tcl) [debian man page]

tell(3tcl)						       Tcl Built-In Commands							tell(3tcl)

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NAME

       tell - Return current access position for an open channel

SYNOPSIS

       tell channelId
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DESCRIPTION

       Returns an integer string giving the current access position in channelId.  This value returned is a byte offset that can be passed to seek
       in order to set the channel to a particular position.  Note that this value is in terms of bytes, not  characters  like	read.	The  value
       returned is -1 for channels that do not support seeking.

       ChannelId  must	be  an	identifier for an open channel such as a Tcl standard channel (stdin, stdout, or stderr), the return value from an
       invocation of open or socket, or the result of a channel creation command provided by a Tcl extension.

EXAMPLE

       Read a line from a file channel only if it starts with foobar:
	      # Save the offset in case we need to undo the read...
	      set offset [tell $chan]
	      if {[read $chan 6] eq "foobar"} {
		  gets $chan line
	      } else {
		  set line {}
		  # Undo the read...
		  seek $chan $offset
	      }

SEE ALSO

       file(3tcl), open(3tcl), close(3tcl), gets(3tcl), seek(3tcl), Tcl_StandardChannels(3tcl)

KEYWORDS

       access position, channel, seeking

Tcl									8.1								tell(3tcl)

flush(3tcl)						       Tcl Built-In Commands						       flush(3tcl)

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NAME

       flush - Flush buffered output for a channel

SYNOPSIS

       flush channelId
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DESCRIPTION

       Flushes any output that has been buffered for channelId.

       ChannelId  must be an identifier for an open channel such as a Tcl standard channel (stdout or stderr), the return value from an invocation
       of open or socket, or the result of a channel creation command provided by a Tcl extension.  The channel must have been opened for writing.

       If the channel is in blocking mode the command does not return until all the buffered output has been flushed to the channel. If the  chan-
       nel  is in nonblocking mode, the command may return before all buffered output has been flushed; the remainder will be flushed in the back-
       ground as fast as the underlying file or device is able to absorb it.

EXAMPLE

       Prompt for the user to type some information in on the console:
	      puts -nonewline "Please type your name: "
	      flush stdout
	      gets stdin name
	      puts "Hello there, $name!"

SEE ALSO

       file(3tcl), open(3tcl), socket(3tcl), Tcl_StandardChannels(3tcl)

KEYWORDS

       blocking, buffer, channel, flush, nonblocking, output

Tcl									7.5							       flush(3tcl)