set list_1 "list1_1 list1_2 list1_3"
set list_2 "list2_1 list2_2 list2_3 list2_4"
set list_3 "list3_1 list3_2"
set list_4 "list4_1 list4_2 list4_3"

proc generation_foreach {} {
    global list_1 list_2 list_3 list_4
 
    set number_combi 0
    foreach element_list_1 $list_1 {
	foreach element_list_2 $list_2 {
	    foreach element_list_3 $list_3 {
		foreach element_list_4 $list_4 {
		    puts "$element_list_1 $element_list_2 $element_list_3 $element_list_4"
		}
	    }
	}
    }
 
return 0
}

set l1 { "abc1" "abc2" "abc3" }
set l2 { "def1" "def2" }
set l3 { "ghi1" "ghi2" "ghi3" }
 
proc combination {head args} {
   if {[llength $args]==0} { return $head }
   set tail [eval combination $args]
   foreach a $head {
      foreach b $tail {
         lappend out [concat $a $b]
      }
   }
   lappend out
   return $out
}
 
putlog [combination $l1 $l2 $l3]