tell(1T) Tcl Built-In Commands tell(1T)______________________________________________________________________________NAMEtell - Return current access position for an open channel
SYNOPSIStell channelId
_________________________________________________________________DESCRIPTION
Returns an integer string giving the current access position in chan‐ │
nelId. 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 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.
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 ALSOfile(1T), open(1T), close(1T), gets(1T), seek(1T), Tcl_StandardChan‐
nels(3TCL)KEYWORDS
access position, channel, seeking
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌────────────────────┬─────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├────────────────────┼─────────────────┤
│Availability │ runtime/tcl-8 │
├────────────────────┼─────────────────┤
│Interface Stability │ Uncommitted │
└────────────────────┴─────────────────┘
NOTES
Source for Tcl is available on http://opensolaris.org.
Tcl 8.1 tell(1T)