TCL : regsub ?

да

нечто новое в русском языке :
на вопрос "Как?" отвечать "Да!"

"EXAMPLES
Replace (in the string in variable string) every instance of foo which is a word by itself with bar:

regsub -all {\<foo\>} $string bar string

Insert double-quotes around the first instance of the word interesting, however it is capitalised.

regsub -nocase {\<interesting\>} $string {"&"} string"
(man regsub)
-------------------------------------------------------------
set templ "любой текст %a еще что-то %b"
foreach {name value} {%a 11 %b 12} {
   regsub -all $name $templ $value templ
   ;# либо так:
   ;# set templ [regsub -all $name $templ $value]
}
puts $templ