Tip : Oracle Home

When you have several oracle_home, here is a way to find which is the oracle home for a particular instance:

1) get the pid of a background process:
ps -edf | grep [o]ra_smon_ORAPRD01
oracle 307694 1 0 Jan 24 - 1:43 ora_smon_ORAPRD01

2) get its current working directory from /proc:
ls -l /proc/307694/cwd
lr-x------ 2 oracle dba 0 Feb 28 16:00 /proc/307694/cwd -> /app/oracle/product/9.2.0/dbs/

Here oracle_home is /app/oracle/product/9.2.0