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tclexecnewlineclipboard

Tcl: can catch { exec } know whether a final newline was output?

Consider the following:

% catch { exec echo "test" } result
0
% catch { exec echo -n "test" } resultnonl
0
% if { $result == $resultnonl } { echo "true" }
true

Question: Is there a way for the two resulting variables to be different?

Use case: I'm retrieving the contents of the clipboard and cannot differentiate between these two cases. In Emacs, it is very common for me to kill (cut) a line without its final newline, and also very common to kill a whole line. The clipboard only differs by the newline.

Solution

  • Check out the -keepnewline flag to exec. Watch:

    catch { exec -keepnewline -- echo "test" } result
string length $result