SQLPLUS not working if I pass variables to Shell Script - bash

Question

I wrote a sample shell script trying to execute a SQL file using SQLPLUS.
Here is my shell script
#!/bin/bash
username=$1
password=$2
TNS_entry=$3
schema_version=$(sqlplus -S '$username/$password#$TNS_entry' #schema.sql)
echo "Schema_number: $schema_version";
#./schema.sh username password '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)
(HOST=SANDBOX.domain)(PORT=1521))(CONNECT_DATA=(SERVER=DEDICATED)
(SERVICE_NAME=orcl))'
After executing this I am getting below SQLPLUS error.
Schema_number: ERROR:
ORA-12154: TNS:could not resolve the connect identifier specified
ERROR:
ORA-12162: TNS:net service name is incorrectly specified
ERROR:
ORA-12162: TNS:net service name is incorrectly specified
However if I run this manually I can connect to Oracle DB with out any issues, that concludes my SQLPLUS connection string has no issues. I am guessing shell is the culprit here, but couldn't figure out where it causing issue.
sqlplus username/password#'(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=SANDBOX.domain)(PORT=1521))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=orcl)))' #schema.sql
SQL*Plus: Release 12.2.0.1.0 Production on Wed Mar 14 21:07:37 2018
Copyright (c) 1982, 2016, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
Can some one take a look at this and help me identify the issue.
Thanks and Regards
Saint

Answer 1

I got this working by editing as below. shell acting weird to parse quotes. Not sure this is ideal solution but this hack served the purpose.
#!/bin/bash
username=$1
password=$2
TNS_entry=$3
schema_version=$(sqlplus -S ''"$username'"/'"$password'"#'"$TNS_entry'"' #schema.sql)
echo "Schema_number: $schema_version";