input textvariable

#!/bin/env tclsh

package require Tk

wm minsize . 640 400

set ::v_btn1 123
set ::lbl1 "Label 1"
set ::lbl2 "Label 2"

set btn1 [button .btn1 -text "Press me" -command {pressMe $::v_btn1}]
#set lbl1 [label .lbl1 -textvariable ::lbl1]
#set lbl2 [label .lbl2 -textvariable ::lbl2]
set lbl1 [label .lbl1 -text "Label 1" -textvariable $::lbl1]
set lbl2 [label .lbl2 -text "Label 2" -textvariable $::lbl2]

pack $btn1 -side top
pack $lbl1 -side top
pack $lbl2 -side top

proc pressMe {x} {
        set ::v_btn1 [expr $x + 1]
        puts $::v_btn1
        global ::lbl1
        set ::lbl1 "Label $::v_btn1"
        puts $::lbl1
}