Tcl C API: redirect stdout of embedded Tcl interp to a file without affecting the whole program

Question

#include 
int main(int argc, char** argv)
{
    Tcl_Interp *interp = Tcl_CreateInterp();

    Tcl_Channel stdoutChannel = Tcl_GetChannel(interp, \"stdout\",         


        

Answer 1

At the level of the C API, and assuming that you are on a Unix-based OS (i.e., not Windows), you can do this far more simply by using the right OS calls:

#include 
#include 

// ... now inside a function

    int fd = open("/home/aminasya/nlb_rundir/imfile", O_WRONLY|O_CREAT, 0744);
    // Important: deal with errors here!

    dup2(fd, STDOUT_FILENO);
    close(fd);

You could also use dup() to save the old stdout (to an arbitrary number that Tcl will just ignore) so that you can restore it later, if desired.