学习shell脚本编程的一次实践，通过shell脚本生成数据库的markdown文档，代码如下：

HOST=xxxxxx PORT=xxxx USER="xxxxx" PASSWORD="xxxxxx" DATABASE_PREFIX="xxxxxx"   QUERY_DATABASE="select distinct TABLE_SCHEMA from information_schema.TABLES where TABLE_TYPE='BASE TABLE'" databaseList=$(mysql -h ${HOST} -u ${USER} -p${PASSWORD} -e "${QUERY_DATABASE}") for database in ${databaseList} do     if [[ ${database} == *${DATABASE_PREFIX}* ]]     then         echo "Start ${database}"         echo "### ${database}" >> test.md         queryTable="select  distinct TABLE_NAME from information_schema.COLUMNS where TABLE_SCHEMA='${database}'"         tableList=$(mysql -h ${HOST} -u ${USER} -p${PASSWORD} -N -e "${queryTable}")         for table in ${tableList}         do                             if [ $(grep -c "#### ${table%_*}_0" test.md) -ne '0' ]              then                 continue             fi                          echo "Start print table:${table}"             echo "#### ${table}" >> test.md             echo "名称 | 类型 | 是否可为空 | Key | 说明" >> test.md             echo "--|--|--|--|--" >> test.md             queryCloumns="select COLUMN_NAME, replace(COLUMN_TYPE,' ',''),IS_NULLABLE,CONCAT(COLUMN_KEY,'+++++++++'),CONCAT(replace(COLUMN_COMMENT,' ',''),'+++++++++') from information_schema.COLUMNS where TABLE_NAME='${table}' and TABLE_SCHEMA='${database}' order by ORDINAL_POSITION"             columnList=$(mysql -h ${HOST} -u ${USER} -p${PASSWORD} -N -e "${queryCloumns}")             count=0             row=""              for column in ${columnList}              do                  row="${row} ${column} | "                  let count++                  if [[ ${count} == 5 ]]                  then                      echo ${row} >> test.md                      count=0                      row=""                  fi              done          done       fi  done