Convert Hive CLI scripts to Beeline

If you have legacy scripts that execute Hive queries from edge nodes using the Hive CLI, you must solve potential incompatibilities with variable substitution in these scripts. HDP 3.0 and later supports Beeline instead of Hive CLI. You can use Beeline to run legacy scripts with a few caveats.

In this task, you resolve incompatibilities in legacy Hive CLI scripts and Beeline:

Configuration variables
- Problem: You cannot refer to configuration parameters in scripts using the hiveconf namespace unless allowed.
- Solution: You include the parameter in the HiveServer whitelist.
Namespace problems
- Problem: Beeline does not support the system and env namespaces for variables.
- Solution: You remove these namespace references from scripts using a conversion technique described in this task.

Create a conversion script named env_to_hivevar.sh that removes env references in your SQL scripts.

#!/usr/bin/env bash
                        
CMD_LINE=""
                        
#Blank conversion of all env scoped values
for I in `env`; do
  CMD_LINE="$CMD_LINE --hivevar env:${I} "
done
echo ${CMD_LINE}

On the command line of a node in your cluster, define and export a variable named HIVEVAR, for example, and set it to execute the conversion script.
```
export HIVEVAR=`./env_to_hivevar.sh`
```
Define and export variables to hold a few variables for testing the conversion.
```
export LOC_TIME_ZONE="US/EASTERN"
export MY_TEST_VAR="TODAY"
```
On the command line of a cluster node, test the conversion: Execute a command that references HIVEVAR to parse a SQL statement, remove the incompatible env namespace, and execute the remaining SQL.
```
hive ${HIVEVAR} -e 'select "${env:LOC_TIME_ZONE}";'
```
```
+-------------+
|     _c0     |
+-------------+
| US/EASTERN  |
+-------------+
```
Create a text file named init_var.sql to simulate a legacy script that sets two configuration parameters, one in the problematic env namespace.
```
set mylocal.test.var=hello;
set mylocal.test.env.var=${env:MY_TEST_VAR};
```
Whitelist these configuration parameters: In Ambari, go to Hive > Configs > Advanced > Custom hiveserver2-site.
Add the property key: hive.security.authorization.sqlstd.confwhitelist.append.
Provide the property value, or values, to whitelist, for example: mylocal\..*|junk.
This action appends mylocal.test.var and mylocal.test.env.var parameters to the whitelist.
Save configuration changes, and restart any components as required.
Execute a command that references HIVEVAR to parse a SQL script, removes the incompatible env namespace, and executes the remaining SQL, including the whitelisted configuration parameters identified by hiveconf:.
```
hive -i init_var.sql ${HIVEVAR} -e 'select "${hiveconf:mylocal.test.var}","${hiveconf:mylocal.test.env.var}";'                  
```
```
+--------+--------+
|  _c0   |  _c1   |
+--------+--------+
| hello  | TODAY  |
+--------+--------+
```