How do you SELECT a value from a table into a Unix variable?

[dba_admin]

Could you please tell me why the first one works but the second fails?


tt=`sqlplus -silent dba_mydb/dba_mydb@mydb < set pagesize 0 feedback off verify off heading off echo off
select count(*) from user_tables;
--select count(*) from v\$log;
exit;
END`
echo $tt

tt=`sqlplus -silent dba_mydb/dba_mydb@mydb < set pagesize 0 feedback off verify off heading off echo off
--select count(*) from user_tables;
select count(*) from v\$log;
exit;
END`
echo $tt

[marist89]

tt=`sqlplus -silent dba_mydb/dba_mydb@mydb <

You have to escape the escape...

[dba_admin]

Thank you. This works!

But, why do I need to escape twice?

[marist89]

This was my thought process the first time I encountered this:

If I run this command from the commandline, I would have to escape the $ so it doesn't get intrepreted as a environment variable.

Since this is inside a script, I have to escape any special characters that will get passed to the command line. Since the \ is a special character, it has to get escaped with \.