Go to main content

man pages section 1: User Commands

Exit Print View

Updated: Wednesday, February 9, 2022

selection (1t)


selection - Manipulate the X selection


selection option ?arg arg ...?


selection(1t)                Tk Built-In Commands                selection(1t)


       selection - Manipulate the X selection

       selection option ?arg arg ...?

       This  command provides a Tcl interface to the X selection mechanism and
       implements the full selection functionality described in the  X  Inter-
       Client Communication Conventions Manual (ICCCM).

       Note  that  for  management of the CLIPBOARD selection (see below), the
       clipboard command may also be used.

       The first argument to selection determines the format of  the  rest  of
       the arguments and the behavior of the command.  The following forms are
       currently supported:

       selection clear ?-displayof window? ?-selection selection?
              If selection exists anywhere on window's display,  clear  it  so
              that  no window owns the selection anymore.  Selection specifies
              the X selection that should be cleared, and should  be  an  atom
              name such as PRIMARY or CLIPBOARD; see the Inter-Client Communi-
              cation  Conventions  Manual  for  complete  details.   Selection
              defaults  to  PRIMARY  and  window  defaults to ".".  Returns an
              empty string.

       selection get ?-displayof window? ?-selection selection? ?-type type?
              Retrieves the value  of  selection  from  window's  display  and
              returns  it as a result.  Selection defaults to PRIMARY and win-
              dow defaults to ".".  Type  specifies  the  form  in  which  the
              selection  is  to  be returned (the desired "target" for conver-
              sion, in ICCCM terminology), and should be an atom name such  as
              STRING  or FILE_NAME; see the Inter-Client Communication Conven-
              tions Manual for complete details.   Type  defaults  to  STRING.
              The selection owner may choose to return the selection in any of
              several  different  representation  formats,  such  as   STRING,
              UTF8_STRING,  ATOM, INTEGER, etc. (this format is different than
              the  selection  type;  see  the  ICCCM  for  all  the  confusing
              details).   If the selection is returned in a non-string format,
              such as INTEGER or ATOM, the selection command  converts  it  to
              string  format  as  a  collection of fields separated by spaces:
              atoms are converted to their textual names, and anything else is
              converted to hexadecimal integers.  Note that selection get does
              not retrieve the selection in the UTF8_STRING format unless told

       selection handle ?-selection s? ?-type t? ?-format f? window command
              Creates a handler for selection requests, such that command will
              be executed whenever selection s is owned by window and  someone
              attempts  to  retrieve it in the form given by type t (e.g. t is
              specified in the selection get command).  S defaults to PRIMARY,
              t  defaults  to STRING, and f defaults to STRING.  If command is
              an empty string then any existing handler for window, t,  and  s
              is  removed.   Note  that  when the selection is handled as type
              STRING it is also automatically handled as type  UTF8_STRING  as

              When  selection is requested, window is the selection owner, and
              type is the requested type, command will be executed  as  a  Tcl
              command  with  two additional numbers appended to it (with space
              separators).  The two additional numbers  are  offset  and  max-
              Chars:   offset  specifies  a starting character position in the
              selection and maxChars gives the maximum number of characters to
              retrieve.   The  command  should return a value consisting of at
              most maxChars of the selection,  starting  at  position  offset.
              For  very  large selections (larger than maxChars) the selection
              will be retrieved using  several  invocations  of  command  with
              increasing  offset  values.   If  command returns a string whose
              length is less than maxChars, the return  value  is  assumed  to
              include all of the remainder of the selection;  if the length of
              command's result is equal  to  maxChars  then  command  will  be
              invoked again, until it eventually returns a result shorter than
              maxChars.  The value of maxChars will always be relatively large
              (thousands of characters).

              If  command  returns  an  error  then the selection retrieval is
              rejected just as if the selection did not exist at all.

              The format argument specifies the representation that should  be
              used to transmit the selection to the requester (the second col-
              umn of Table 2 of the ICCCM), and defaults to STRING.  If format
              is  STRING,  the selection is transmitted as 8-bit ASCII charac-
              ters (i.e.  just in the form returned by command, in the  system
              encoding; the UTF8_STRING format always uses UTF-8 as its encod-
              ing).  If format is ATOM, then the return value from command  is
              divided  into  fields  separated  by white space;  each field is
              converted to its atom value, and the 32-bit atom value is trans-
              mitted  instead  of  the  atom  name.  For any other format, the
              return value from command 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.

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

       selection own ?-displayof window? ?-selection selection?

       selection own ?-command command? ?-selection selection? window
              The  first  form  of  selection own returns the path name of the
              window in this application that owns selection  on  the  display
              containing  window,  or  an  empty  string  if no window in this
              application owns the selection.  Selection defaults  to  PRIMARY
              and window defaults to ".".

              The second form of selection own causes window to become the new
              owner of selection  on  window's  display,  returning  an  empty
              string  as  result. The existing owner, if any, is notified that
              it has lost the selection.  If command is specified, it is a Tcl
              script to execute when some other window claims ownership of the
              selection away from window.  Selection defaults to PRIMARY.

       On X11 platforms, one of the standard selections available is the  SEC-
       ONDARY  selection.  Hardly anything uses it, but here is how to read it
       using Tk:

              set selContents [selection get -selection SECONDARY]

       Many different types of data may be available for a selection; the spe-
       cial type TARGETS allows you to get a list of available types:

              foreach type [selection get -type TARGETS] {
                 puts "Selection PRIMARY supports type $type"

       To  claim  the selection, you must first set up a handler to supply the
       data for the selection. Then you have to claim the selection...
              # Set up the data handler ready for incoming requests
              set foo "This is a string with some data in it... blah blah"
              selection handle -selection SECONDARY . getData
              proc getData {offset maxChars} {
                 puts "Retrieving selection starting at $offset"
                 return [string range $::foo $offset [expr {$offset+$maxChars-1}]]

              # Now we grab the selection itself
              puts "Claiming selection"
              selection own -command lost -selection SECONDARY .
              proc lost {} {
                 puts "Lost selection"

       See attributes(7) for descriptions of the following attributes:

       |Availability   | runtime/tk-8     |
       |Stability      | Uncommitted      |


       clear, format, handler, ICCCM, own, selection, target, type

       Source code for open source software components in Oracle  Solaris  can
       be found at https://www.oracle.com/downloads/opensource/solaris-source-

       This    software    was    built    from    source     available     at
       https://github.com/oracle/solaris-userland.    The  original  community
       source        was        downloaded        from         https://source-

       Further information about this software can be found on the open source
       community website at https://www.tcl.tk/.

Tk                                    8.1                        selection(1t)