`exec my_executable_that_seg_faults > /dev/null`;
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exec at the start of a command is one of the few things that are treated specially in Perl_do_exec3(), see Re^2: Improve pipe open? (redirect hook). It seems to disable the default optimization and forces the use of the default shell.

There is a way to stay mentally sane on Unix/POSIX systems for I/O-redirection. Don't use system; instead, fork and exec manually:

# (untested)
my $pid=fork();
my @cmd_and_args=('my_executable_that_seg_faults');
# maybe push @cmd_and_args,qw( some arguments for the program );
defined($pid) or die "Can't fork: $!";
if ($pid) {
    # parent process
    waitpid $pid; #<-- sets $?
} else {
    # child process
    open STDOUT,'>','/dev/null' or die "Can't redirect STDOUT: $!";
    exec { $cmd_and_args[0] } @cmd_and_args;
    die "exec failed: $!";
}
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Note that ONLY indirect object notation on exec prevents all attempts of perl to be smart. See The problem of "the" default shell.

Alexander