Manual Pages for UNIX Operating System command usage for man tell

Tcl Built-In Commands                                    tell(1T)



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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  particu-  |
     lar  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(1T),   open(1T),   close(1T),    gets(1T),    seek(1T),
     Tcl_StandardChannels(3TCL)


KEYWORDS
     access position, channel, seeking

ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:






Tcl                     Last change: 8.1                        1






Tcl Built-In Commands                                    tell(1T)



     _______________________________________
    |   ATTRIBUTE TYPE   |  ATTRIBUTE VALUE|
    |____________________|__________________|_
    | Availability       |  runtime/tcl-8  |
    |____________________|__________________|_
    | Interface Stability|  Uncommitted    |
    |____________________|_________________|

NOTES
     Source for Tcl is available on http://opensolaris.org.













































Tcl                     Last change: 8.1                        2