如何从Shell脚本捕获HBase Shell的输出

Question

I need to fetch records from hbase shell and print it to the output file below is what i have

while IFS="=" read name value
do
query=$(echo "get '/tables/${table_name}','${value}',{COLUMNS=>['cf2:CDC_TS','cf2:CDC_FLAG','cf:ROW_STS_CD']}" | hbase shell ) 
OUT=`tail "$query"`
echo "${OUT}" >> /results_${table_name}_${DATE_TIME}.txt
done < /Hbase_retrieve.properties

When i try the above i get

**

HBase Shell; enter 'help<RETURN>' for list of supported commands.
Type "exit<RETURN>" to leave the HBase Shell
Version 1.1.8-mapr-1710, r2c52ca3f992cced95f36b11d7b04b86474ad9ed0, Sun Nov 12 23:59:09 UTC 2017

Not all HBase shell commands are applicable to MapR tables.
Consult MapR documentation for the list of supported commands.

get '/tables/$table_name','row_key',{COLUMNS=>['cf2:CDC_TS','cf2:CDC_FLAG','cf:ROW_STS_CD']}
COLUMN  CELL
 cf:ROW_STS_CD timestamp=1506562033493, value=A
 cf2:CDC_FLAG timestamp=1506562033493, value=U
 cf2:CDC_TS timestamp=1506562033493, value=2017-09-27 20:27:13.493
3 row(s) in 0.1990 seconds

**

how do i eliminate those and just lines and just get below printed to the output

get '/tables/$table_name','row_key',{COLUMNS=>['cf2:CDC_TS','cf2:CDC_FLAG','cf:ROW_STS_CD']}
COLUMN  CELL
 cf:ROW_STS_CD timestamp=1506562033493, value=A
 cf2:CDC_FLAG timestamp=1506562033493, value=U
 cf2:CDC_TS timestamp=1506562033493, value=2017-09-27 20:27:13.493

Answer 1

If you want to write the output to the file but skip the first part (7 lines), you can use tail for that job:

echo "${out}" | tail -n +7 >> /results_${table_name}_${DATE_TIME}.txt 

The + sign indicated to tail that you wan't to skip N lines. From tail --help :

-n, --lines=[+]NUM       output the last NUM lines, instead of the last 10;
                         or use -n +NUM to output starting with line NUM

---

Edit: Oh, and if you want to remove the last time too:

echo "${out}" | tail -n +7 | head -n -1 >> /results_${table_name}_${DATE_TIME}.txt 

Basically the same thing, just the other way around. For completeness, head --help :

-n, --lines=[-]NUM       print the first NUM lines instead of the first 10;
                         with the leading '-', print all but the last
                         NUM lines of each file