-bash-4.2$ id
uid=501(oracle) gid=1000(oinstall) groups=1000(oinstall),1001(dba)

-bash-4.2$ cat rdbms/lib/config.c

/*  SS_DBA_GRP defines the UNIX group ID for sqldba adminstrative access.  */
/*  Refer to the Installation and User's Guide for further information.  */

/* IMPORTANT: this file needs to be in sync with
              rdbms/src/server/osds/config.c, specifically regarding the
              number of elements in the ss_dba_grp array.
 */

#if 0
/*
 * Linux x86_64 assembly code corresponding to C code below. This module
 * can be compiled both as C and ASM module, when changing code here
 * please keep both versions in sync.
 */

        .section .rodata.str1.4, "aMS",@progbits,1
        .align 4
.Ldba_string:     .string "dba"
.Loper_string:    .string "dba"
.Lasm_string:     .string ""
.Lbkp_string:     .string "dba"
.Ldgd_string:     .string "dba"
.Lkmt_string:     .string "dba"

        .section        .rodata
        .align 8
        .globl ss_dba_grp
ss_dba_grp:
        .quad   .Ldba_string
        .quad   .Loper_string
        .quad   .Lasm_string
        .quad   .Lbkp_string
        .quad   .Ldgd_string
        .quad   .Lkmt_string
        .type   ss_dba_grp,@object
        .size   ss_dba_grp,.-ss_dba_grp
        .section .note.GNU-stack, ""
        .end
/*
 * Assembler will not parse a file past the .end directive
 */
#endif

#define SS_DBA_GRP "dba"
#define SS_OPER_GRP "dba"
#define SS_ASM_GRP ""
#define SS_BKP_GRP "dba"
#define SS_DGD_GRP "dba"
#define SS_KMT_GRP "dba"

const char * const ss_dba_grp[] = 
     {SS_DBA_GRP, SS_OPER_GRP, SS_ASM_GRP,
      SS_BKP_GRP, SS_DGD_GRP, SS_KMT_GRP};  

SQL> show parameter passw

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
remote_login_passwordfile            string      EXCLUSIVE

SQL> select * from v$pwfile_users;

USERNAME                       SYSDB SYSOP SYSAS
------------------------------ ----- ----- -----
SYS                            TRUE  TRUE  FALSE

cat /etc/oratab
#Backup file is  /grid/app/grid/product/crsdata/atc-srv-olap1/output/oratab.bak.atc-srv-olap1.grid line added by Agent
#



# This file is used by ORACLE utilities.  It is created by root.sh
# and updated by either Database Configuration Assistant while creating
# a database or ASM Configuration Assistant while creating ASM instance.

# A colon, ':', is used as the field terminator.  A new line terminates
# the entry.  Lines beginning with a pound sign, '#', are comments.
#
# Entries are of the form:
#   $ORACLE_SID:$ORACLE_HOME:<N|Y>:
#
# The first and second fields are the system identifier and home
# directory of the database respectively.  The third field indicates
# to the dbstart utility that the database should , "Y", or should not,
# "N", be brought up at system boot time.
#
# Multiple entries with the same $ORACLE_SID are not allowed.
#
#
+ASM:/grid19:N          # line added by Agent
You have mail in /var/spool/mail/oracle
-bash-4.2$ dbhome
/oracle
-bash-4.2$ echo $ORACLE_HOME
/oracle/app/oracle/product/12.1.0/dbhome_3
-bash-4.2$ echo $PATH
/usr/lib64/qt-3.3/bin:/usr/local/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/oracle/app/oracle/product/12.1.0/dbhome_3/bin:/oracle/app/oracle/product/12.1.0/dbhome_3/bin
You have mail in /var/spool/mail/oracle
-bash-4.2$ echo $ORACLE_SID
olapn
-bash-4.2$ type sqlplus
sqlplus is hashed (/oracle/app/oracle/product/12.1.0/dbhome_3/bin/sqlplus)
-bash-4.2$ ps -fu oracle | grep dbw
oracle   34522     1  0 Oct21 ?        00:03:34 ora_dbw0_olapn
oracle   34524     1  0 Oct21 ?        00:03:49 ora_dbw1_olapn
oracle   34526     1  0 Oct21 ?        00:04:57 ora_dbw2_olapn
oracle   34528     1  0 Oct21 ?        00:03:36 ora_dbw3_olapn
oracle   34530     1  0 Oct21 ?        00:06:30 ora_dbw4_olapn
oracle   34532     1  0 Oct21 ?        00:03:19 ora_dbw5_olapn
oracle   34534     1  0 Oct21 ?        00:03:13 ora_dbw6_olapn
oracle   34536     1  0 Oct21 ?        00:03:30 ora_dbw7_olapn
oracle   43363 31871  0 08:11 pts/0    00:00:00 grep --color=auto dbw