Type specifies the form in which the selection is to be returned (the desired “target” for conversion, in ICCCM terminology), and should be an atom name such as STRING or FILE_NAME; see the Inter-Client Communication Conventions Manual for complete details. Type defaults to STRING.

The format argument specifies the representation that should be used to transmit the selection to the requester (the second column of Table 2 of the ICCCM), and defaults to STRING. If format is STRING, the selection is transmitted as 8-bit ASCII characters. If format is ATOM, then the data is divided into fields separated by white space; each field is converted to its atom value, and the 32-bit atom value is transmitted instead of the atom name. For any other format, data is divided into fields separated by white space and each field is converted to a 32-bit integer; an array of integers is transmitted to the selection requester. Note that strings passed to clipboard append are concatenated before conversion, so the caller must take care to ensure appropriate spacing across string boundaries. All items appended to the clipboard with the same type must have the same format.

The format argument is needed only for compatibility with clipboard requesters that do not use Tk. If the Tk toolkit is being used to retrieve the CLIPBOARD selection then the value is converted back to a string at the requesting end, so format is irrelevant.

A -- argument may be specified to mark the end of options: the next argument will always be used as data. This feature may be convenient if, for example, data starts with a -.

Note that on modern X11 systems, the most useful type to retrieve for transferred strings is not STRING, but rather UTF8_STRING.

if {[catch {clipboard get} contents]} {
    # There were no clipboard contents at all
}

clipboard clear
clipboard append "some fixed string"

# This is a very simple canvas serializer;
# it produces a script that recreates the item(s) when executed
proc getItemConfig {canvas tag} {
   set script {}
   foreach item [$canvas find withtag $tag] {
      append script {$canvas create } [$canvas type $item]
      append script { } [$canvas coords $item] { }
      foreach config [$canvas itemconf $item] {
         lassign $config name - - - value
         append script [list $name $value] { }
      }
      append script \n
   }
   return [string trim $script]
}
# Set up a binding on a canvas to cut and paste an item
set c [canvas .c]
pack $c
$c create text 150 30 -text "cut and paste me"
bind $c <<Cut>> {
   clipboard clear
   clipboard append -type TkCanvasItem \
         [getItemConfig %W current]
   # Delete because this is cut, not copy.
   %W delete current
}
bind $c <<Paste>> {
   catch {
      set canvas %W
      eval [clipboard get -type TkCanvasItem]
   }
}