What am I missing?

$ cat 1.bliako.pl 
#!/usr/bin/perl

# setenv from within perl to effect parent shell
# actually parent should be more appropriately
# called "adopted" or "step-parent", re execl
# there is one little requirement:
# you should run this program via shell's exec:
#    % exec <scriptname>
#
# author: bliako
# date: 09/07/2018

use Inline C => DATA;

# ...

# this should be the last statement in your script
# because nothing else will be executed after that
# not even the 'or die ...'
mysetenv("test", "TURE") or die "mysetenv() failed";


__END__
__C__

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

int mysetenv(const char *K, const char *V){
        if( K==NULL || V==NULL ){ return 0; }
        char *shell = getenv("SHELL");
        if( setenv(K, V, 1) ){
                fprintf(stderr, "mysetenv() : call to setenv() has fai
+led.\n");
                return 1;
        }
        // replace caller shell with a new shell which now has
        // set this new env var
        //printf("shell to exec is %s\n", shell);
        execl(shell, NULL, NULL);
        perror("execl failed, ");
        return 1;
}

$
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