linux shell echo 没有写入到指定的文件

下面输出ABCD到MAIL_BODY里面去，CD都能输出了，为什么AB就是写不进去呢？

grep -sl "coloar" ${LOG_DIR}/IYECMA9D*.log > ${TMP_FILE}  2>> ${LOG_FILE}
grep -sl "olderr" ${LOG_DIR}/IYECMA9D*.log > ${TMP_FILE2}  2>> ${LOG_FILE}

##
MAIL_LST="/ryu1/common/rls/param/iyec_teijyo_check_mail.lst"
MAIL_FROM=`grep "MAIL_FROM" ${MAIL_LST} | awk -F"=" '{print $2}' | sed 's/"//g'`

MAIL_TO=`grep "MAIL_TO" ${MAIL_LST} | awk -F"=" '{print $2}' | sed 's/"//g'`
MAIL_TITLE=`grep "MAIL_TITLE" ${MAIL_LST} | awk -F"=" '{print $2}' | sed 's/"//g'`
# 
if  [ -s ${TMP_FILE} ] || [ -s ${TMP_FILE2} ]
then
echo "A"  >>  ${MAIL_BODY}
echo "B"  >>  ${MAIL_BODY}
  if  [ -s ${TMP_FILE} ]
  then
    echo "" > ${MAIL_BODY}
    echo "C"  >>  ${MAIL_BODY}
    cat ${TMP_FILE} >>  ${MAIL_BODY}  2>> ${LOG_FILE}
  fi
  if  [ -s ${TMP_FILE2} ]
  then
echo ""  >>  ${MAIL_BODY}
    echo "D"  >>  ${MAIL_BODY}
    cat ${TMP_FILE2} >>  ${MAIL_BODY}  2>> ${LOG_FILE}
  fi
else
echo "E"  >>  ${MAIL_BODY}
fi

因为你这行代码会清空覆盖echo "" > ${MAIL_BODY}

你把>改成>>就好了

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