Question

Within my Tcl script I’m building source code in another language. Let it be gnuplot source for example. I have Tcl code like this:

# `script' variable contains gnuplot source code
set script {
  set terminal pdf
  set output "chart.pdf"
  set title "[makeTitle]"
  plot "$dataFile" using 1:2 title ""
}

# Then I write `script' to file for later execution

Notice that script variable contains command call (makeTitle) and variable substitution (dataFile). The source code itself contains new lines, double quotes.

Question: how can I simply “evaluate” this variable to substitute command calls by their results and variables by their values? Expected result should look like this:

  set terminal pdf
  set output "chart.pdf"
  set title "R(S) Dependence"
  plot "r_s.txt" using 1:2 title ""

Answer 1

You’re looking for the subst command:

set result [subst $script]