How can I redirect stdout into a file in tcl

Question

how can I redirect a proc output into a file in tcl, for example, I have a proc foo, and would like to redirect the foo output into a file bar. But got this result

Answer 1

We can try in this way also

% proc foo {} { return "hello world" }

% foo

hello world

% set fd [open "a.txt" w]

file5

% set val [foo]

hello world

% puts $fd $val

% close $fd

% set data [exec cat a.txt]

hello world