atコマンドを使用したときに表示される警告メッセージを削除する[重複]

私はbash設定ファイルでコマンドを使用してat時間をエコーし​​て時間を思い出させますが、今コマンドラインを開くと、次の迷惑な警告がたくさん点滅します。

warning: commands will be executed using /bin/sh
job 241 at Thu Sep  1 00:00:00 2016
warning: commands will be executed using /bin/sh
job 242 at Thu Sep  1 01:00:00 2016
warning: commands will be executed using /bin/sh
job 243 at Thu Sep  1 02:00:00 2016
warning: commands will be executed using /bin/sh
job 244 at Thu Sep  1 03:00:00 2016
warning: commands will be executed using /bin/sh
job 245 at Thu Sep  1 04:00:00 2016
warning: commands will be executed using /bin/sh
job 246 at Thu Sep  1 05:00:00 2016
warning: commands will be executed using /bin/sh
job 247 at Thu Sep  1 06:00:00 2016
warning: commands will be executed using /bin/sh
job 248 at Thu Sep  1 07:00:00 2016
warning: commands will be executed using /bin/sh
job 249 at Thu Sep  1 08:00:00 2016
warning: commands will be executed using /bin/sh
job 250 at Thu Sep  1 09:00:00 2016
warning: commands will be executed using /bin/sh
job 251 at Wed Aug 31 10:00:00 2016
warning: commands will be executed using /bin/sh
job 252 at Wed Aug 31 11:00:00 2016
warning: commands will be executed using /bin/sh
job 253 at Wed Aug 31 12:00:00 2016
warning: commands will be executed using /bin/sh
job 254 at Wed Aug 31 13:00:00 2016
warning: commands will be executed using /bin/sh
job 255 at Wed Aug 31 14:00:00 2016
warning: commands will be executed using /bin/sh
job 256 at Wed Aug 31 15:00:00 2016
warning: commands will be executed using /bin/sh
job 257 at Wed Aug 31 16:00:00 2016
warning: commands will be executed using /bin/sh
job 258 at Wed Aug 31 17:00:00 2016
warning: commands will be executed using /bin/sh
job 259 at Wed Aug 31 18:00:00 2016
warning: commands will be executed using /bin/sh
job 260 at Wed Aug 31 19:00:00 2016
warning: commands will be executed using /bin/sh
job 261 at Wed Aug 31 20:00:00 2016
warning: commands will be executed using /bin/sh
job 262 at Wed Aug 31 21:00:00 2016
warning: commands will be executed using /bin/sh
job 263 at Wed Aug 31 22:00:00 2016
warning: commands will be executed using /bin/sh
job 264 at Wed Aug 31 23:00:00 2016

私が実行したいコマンドは例です。

echo "midnight" | at 00:00

これらの警告をどのように削除できますか？

at注：これは、「コマンドを実行するために/ bin / shを使用するという警告が表示されるのはなぜですか？他のシェルが必要な場合はどうなりますか？」という質問とは異なります。警告を削除する方法とシェルに関する情報を知りたくありません。