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

Hyper-V Linux Client Can't Talk To Network

#tail -f /var/log/messages

#tail -f -n 200 /var/log/messages

Eventually dmesg fills up with noise like:

eth2: 21140 transmit timed out, status fc6981c7, SIA fffffe00 00000068 00000070 fffffec8, resetting...
(or whatever your eth device is).

Solution:

# chkconfig irqbalance off 

# reboot


(Source)

How to resolve error "-bash: fork: retry: Resource temporarily unavailable" launching wsadmin scripts

Increasing the value of the ulimit -u (NPROC - max user processes) setting will prevent and eliminate the problem.

Check the current values of ulimit settings by issuing the following command as root (superuser) user:

ulimit -a

Red Hat Enterprise Linux v6 has default values of 1024 for both ulimit -u (nproc : maximum user processes) and ulimit -n (nofiles : open files : file descriptors) which are grossly inadequate for WebSphere environments.

WebSphere Support recommends a value of '131072' for NPROC. Engage the Unix / Linux System Administrator, to login to the affected Linux system or server as root (superuser) user, and issue the following command:

ulimit -u 131072

The value of the ulimit -n (NOFILES) setting should also be increased to the recommended value of '65536' at the same time, if it is at the default value of 1024, or a lower value than 65536, in order to prevent a variety of failures in WebSphere environments that can occur during install, update, jvm startup, application startup, administration, and application deployment operations, by issuing the following command as root user:

ulimit -n 65536

https://www.ibm.com/developerworks/community/blogs/aimsupport/entry/resolve_too_many_open_files_error_and_native_outofmemory_due_to_failed_to_create_thread_issues_in_websphere_application_server_running_on_linux?lang=en

https://access.redhat.com/solutions/543503

CHANGE SYS PASSWORD IN ORACLE

1. Re-create password file

If you want to reset the password of sys. you can recreate the password file with below cmd.
$ orapwd
Usage: orapwd file=<fname> password=<password> entries=<users> force=<y/n> nosysdba=<y/n>
where
file – name of password file (mand),
password – password for SYS (mand),
entries – maximum number of distinct DBA,
force – whether to overwrite existing file (opt),
nosysdba – whether to shut out the SYSDBA logon (opt for Database Vault only).
There are no spaces around the equal-to (=) character.


[root@test devapps]# su - oradev
[oradev@test ~]$ . /u01/dev/devdb/tech_st/11.2.0/DEV_test.env
[oradev@test ~]$ orapwd file=$ORACLE_HOME/dbs/orapwDEV password=oracle entries=30

2. Type the following commands:

$ sqlplus "/ as sysdba"

 SQL> ALTER USER SYS IDENTIFIED BY [password]; 

 SQL> ALTER USER SYSTEM IDENTIFIED BY [password];