simplify command into finally accepted and portable form

postfix/postfix.spec

@@ -326,7 +326,7 @@ Conflicts:    exim, sendmail, ssmtp
         #   after upgrade, regenerate configuration
         ( cd $RPM_INSTALL_PREFIX/etc/postfix && %{l_make} clean all; true ) >/dev/null 2>&1
         #   after upgrade, restore status
-        { eval `cat %{l_tmpfile}`; rm -f %{l_tmpfile}; true; }
+        eval `cat %{l_tmpfile}`; rm -f %{l_tmpfile} >/dev/null 2>&1 || true
         [ ".$postfix_active" = .yes ] && %{l_rc} postfix start
     fi
     exit 0