seek(n) Tcl (7.5) seek(n)
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NAME
seek - Change the access position for an open channel
SYNOPSIS
seek channelId offset ?origin?
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DESCRIPTION
Changes the current access position for channelId.
ChannelId must be a channel identifier such as returned from
a previous invocation of open or socket. 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 command returns, even if the channel is in
nonblocking mode. It also discards 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.
KEYWORDS
access position, file, seek
Page 1 (printed 2/19/99)
