# echo its $DESKTOP_STARTUP_ID. We (blockingly) read the variable into
# $startup_id in the testcase.
my $tmp = tmpnam();
-mkfifo($tmp, 0600) or BAIL_OUT "Could not create FIFO in $tmp";
+mkfifo($tmp, 0600) or BAIL_OUT "Could not create FIFO in $tmp: $!";
cmd qq|exec echo \$DESKTOP_STARTUP_ID >$tmp|;