Find ORACLE_SID

There are several commands, some internal and some external to Oracle that will find your current ORACLE_SID.  Within Oracle (SQL*Plus) you can display your ORACLE_SID with any of these commands:

SQL>  select distinct sid from v$mystat;

SQL>  select * from global_name;

SQL>  select instance from v$thread;

SQL> select name from v$database;

There are also external commands that show the current settings for the ORACLE_SID variable:

[oradev@test ~]$ . /u01/dev/devdb/tech_st/11.2.0/DEV_test.env

[oradev@test ~]$ ps -ef | grep pmon

oradev 8034 1 0 Jan29 ? 00:00:34 ora_pmon_DEV
orarman 19983 1 0 2017 ? 00:19:40 ora_pmon_rmandb
oradev 29537 29494 0 12:00 pts/6 00:00:00 grep pmon