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seek(n)			     Tcl Built-In Commands		       seek(n)


       seek - Change the access position for an open channel

       seek channelId offset ?origin?

       Changes the current access position for channelId.

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

       The offset and origin arguments specify the position at which the  next
       read  or	 write	will  occur  for  channelId. Offset must be an integer
       (which may be negative) and origin must be one of the following:

       start	 The new access position will be offset bytes from  the	 start
		 of the underlying file or device.

       current	 The new access position will be offset bytes from the current
		 access position; a negative offset moves the access  position
		 backwards in the underlying file or device.

       end	 The  new access position will be offset bytes from the end of
		 the file or device.  A	 negative  offset  places  the	access
		 position before the end of file, and a positive offset places
		 the access position after the end of file.

       The origin argument defaults to start.

       The command flushes all buffered output for the channel before the com‐
       mand returns, even if the channel is in nonblocking mode.  It also dis‐
       cards any buffered and unread input.  This  command  returns  an	 empty
       string.	 An  error occurs if this command is applied to channels whose
       underlying file or device does not support seeking.

       Note that offset values are byte offsets, not character offsets.	  Both │
       seek and tell operate in terms of bytes, not characters, unlike read.

       Read a file twice:
	      set f [open file.txt]
	      set data1 [read $f]
	      seek $f 0
	      set data2 [read $f]
	      close $f
	      # $data1 == $data2 if the file wasn't updated

       Read the last 10 bytes from a file:
	      set f [open]
	      # This is guaranteed to work with binary data but
	      # may fail with other encodings...
	      fconfigure $f -translation binary
	      seek $f -10 end
	      set data [read $f 10]
	      close $f

       file(n), open(n), close(n), gets(n), tell(n), Tcl_StandardChannels(3)

       access position, file, seek

Tcl				      8.1			       seek(n)
                             _         _         _ 
                            | |       | |       | |     
                            | |       | |       | |     
                         __ | | __ __ | | __ __ | | __  
                         \ \| |/ / \ \| |/ / \ \| |/ /  
                          \ \ / /   \ \ / /   \ \ / /   
                           \   /     \   /     \   /    
                            \_/       \_/       \_/ 
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