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seek(n) - seek, seek - Change the access position for an open channel - man n seek

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



NAME
       seek - Change the access(2,5) position for an open(2,3,n) channel

SYNOPSIS
       seek channelId offset ?origin?


DESCRIPTION
       Changes the current access(2,5) position for channelId.

       ChannelId must be an identifier for an open(2,3,n) channel such as a Tcl stan-
       dard channel (stdin, stdout, or stderr), the return value from an invo-
       cation  of  open(2,3,n) or socket(2,7,n), 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(2,n,1 builtins)  or  write(1,2)  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(2,5) position will be offset bytes from  the  start
                 of the underlying file(1,n) or device.

       current   The new access(2,5) position will be offset bytes from the current
                 access(2,5) position; a negative offset moves the access(2,5)  position
                 backwards in(1,8) the underlying file(1,n) or device.

       end       The  new access(2,5) position will be offset bytes from the end of
                 the file(1,n) or device.  A  negative  offset  places  the  access(2,5)
                 position before the end of file(1,n), and a positive offset places
                 the access(2,5) 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(3,n) the channel is in(1,8) nonblocking mode.  It also dis-
       cards any buffered and unread input.  This  command  returns  an  empty
       string.   An  error(8,n) occurs if(3,n) this command is applied to channels whose
       underlying file(1,n) or device does not support seeking.

       Note that offset values are byte offsets, not character offsets.   Both
       seek and tell operate in(1,8) terms of bytes, not characters, unlike read(2,n,1 builtins).


SEE ALSO
       file(1,n)(n), open(2,3,n)(n), close(2,7,n)(n), gets(3,n)(n), tell(n), Tcl_StandardChannels(3)


KEYWORDS
       access(2,5) position, file(1,n), seek



Tcl                                   8.1                              seek(n)

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