ORACLE DATABASE PROBLEM AND SOLUTIONS

Tuesday, May 23, 2023

How to setup SSH Passwordless Login in Linux ?

Setup SSH Passwordless Login in Linux for oracle user

Source server : 10.1.1.1

Target server : 10.1.1.2

Genrate SSH key pair

[oracle@10.1.1.1]$ ssh-keygen

Generating public/private rsa key pair.

Enter file in which to save the key (/home/oracle/.ssh/id_rsa):

Enter passphrase (empty for no passphrase):

Enter same passphrase again:

Your identification has been saved in /home/oracle/.ssh/id_rsa.

Your public key has been saved in /home/oracle/.ssh/id_rsa.pub.

The key fingerprint is:

SHA256:CQIzV4K1UyZ/7WmRtLTyPb1N3EHRXoZj4W09bbcQtDk oracle@ip-10.1.1.1.ec2.internal

The key's randomart image is:

+---[RSA 3072]----+

| +o=.+ o .o.=o|

| .= B + + .O.*|

| + o o * E.*O|

| o o = + .o+B|

| S = o ..+|

| . . + |

| . .|

| |

+----[SHA256]-----+

[oracle@10.1.1.1]$

Upload SSH Key to target server – 10.1.1.2

ssh-copy-id oracle@10.1.1.2

[oracle@10.1.1.1]$

[oracle@10.1.1.1]$ ssh-copy-id oracle@10.1.1.2

/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/home/oracle/.ssh/id_rsa.pub"

The authenticity of host '172.31.21.233 (172.31.21.233)' can't be established.

ECDSA key fingerprint is SHA256:0cU9N1c6iec4IMkhQeT8s7FmzF04X0iLy8pytlr1JCk.

Are you sure you want to continue connecting (yes/no/[fingerprint])? yes

/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed

/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys

oracle@172.31.21.233's password:

Number of key(s) added: 1

Now try logging into the machine, with: "ssh 'oracle@10.1.1.2"

and check to make sure that only the key(s) you wanted were added.

[oracle@10.1.1.1]$

Test and validate passwordless login

Option:1

[oracle@10.1.1.1]$

[oracle@10.1.1.1]$ ssh oracle@10.1.1.2

Create an account or view all your systems at https://red.ht/insights-dashboard

Last login: Tue May 23 16:57:35 2023

[oracle@10.1.1.2 ~]$

Option:2

[oracle@10.1.1.1]$ ssh -l oracle 10.1.1.2

Create an account or view all your systems at https://red.ht/insights-dashboard

Last login: Tue May 23 17:06:21 2023 from 10.1.1.1

[oracle@10.1.1.2]$

How to Set Timezone Using timedatectl Command in Linux ?

Set Timezone Using timedatectl Command in Linux

Check current time and timezone details :

option:1

[root@0.0.0.0]#

[root@0.0.0.0]# timedatectl status

Local time: Tue 2023-05-23 13:53:08 UTC

Universal time: Tue 2023-05-23 13:53:08 UTC

RTC time: Tue 2023-05-23 13:53:09

Time zone: UTC (UTC, +0000)

System clock synchronized: yes

NTP service: active

RTC in local TZ: no

[root@0.0.0.0]#

Option:2

[root@0.0.0.0]#

[root@0.0.0.0]# timedatectl

Local time: Tue 2023-05-23 13:57:09 UTC

Universal time: Tue 2023-05-23 13:57:09 UTC

RTC time: Tue 2023-05-23 13:57:10

Time zone: UTC (UTC, +0000)

System clock synchronized: yes

NTP service: active

RTC in local TZ: no

[root@0.0.0.0]#

Get Timezone name using timedatectl:

[root@0.0.0.0]#

[root@0.0.0.0]# timedatectl list-timezones | grep -i kolkata

Asia/Kolkata

[root@0.0.0.0]#

Set timezone using timedatectl command :

[root@0.0.0.0]#

[root@0.0.0.0]# timedatectl set-timezone "Asia/Kolkata"

[root@0.0.0.0]#

Validate time and timezone

[root@0.0.0.0]#

[root@0.0.0.0]# timedatectl

Local time: Tue 2023-05-23 19:28:34 IST

Universal time: Tue 2023-05-23 13:58:34 UTC

RTC time: Tue 2023-05-23 13:58:35

Time zone: Asia/Kolkata (IST, +0530)

System clock synchronized: yes

NTP service: active

RTC in local TZ: no

[root@0.0.0.0]#

Monday, May 22, 2023

Error : -bash: ifconfig: command not found

Login as root user :

[root@0.0.0.0]#

[root@0.0.0.0]# ifconfig

-bash: ifconfig: command not found

[root@0.0.0.0]#

Install net-tools package using yum command

[root@0.0.0.0]# yum install net-tools

Updating Subscription Management repositories.

Unable to read consumer identity

This system is not registered with an entitlement server. You can use subscription-manager to register.

Last metadata expiration check: 0:01:33 ago on Mon 22 May 2023 04:36:53 PM UTC.

Dependencies resolved.

==============================================================================================================================

Package Architecture Version Repository Size

==============================================================================================================================

Installing:

net-tools x86_64 2.0-0.52.20160912git.el8 rhel-8-baseos-rhui-rpms 322 k

Transaction Summary

==============================================================================================================================

Install 1 Package

Total download size: 322 k

Installed size: 942 k

Is this ok [y/N]: y

Downloading Packages:

net-tools-2.0-0.52.20160912git.el8.x86_64.rpm 9.4 MB/s | 322 kB 00:00

------------------------------------------------------------------------------------------------------------------------------

Total 6.1 MB/s | 322 kB 00:00

Running transaction check

Transaction check succeeded.

Running transaction test

Transaction test succeeded.

Running transaction

Preparing : 1/1

Installing : net-tools-2.0-0.52.20160912git.el8.x86_64 1/1

Running scriptlet: net-tools-2.0-0.52.20160912git.el8.x86_64 1/1

Verifying : net-tools-2.0-0.52.20160912git.el8.x86_64 1/1

Installed products updated.

Installed:

net-tools-2.0-0.52.20160912git.el8.x86_64

Complete!

[root@0.0.0.0]#

[root@0.0.0.0]# ifconfig

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 9001

inet 172.21.31.211 netmask 255.255.240.0 broadcast 172.31.31.255

inet6 f80::6:3ccf:fe7d:1a13 prefixlen 64 scopeid 0x20<link>

ether 0a:76:33:7d:1a:13 txqueuelen 1000 (Ethernet)

RX packets 86484 bytes 127950677 (122.0 MiB)

RX errors 0 dropped 0 overruns 0 frame 0

TX packets 11182 bytes 1084233 (1.0 MiB)

TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536

inet 127.0.0.1 netmask 255.0.0.0

inet6 ::1 prefixlen 128 scopeid 0x10<host>

loop txqueuelen 1000 (Local Loopback)

RX packets 509 bytes 77514 (75.6 KiB)

RX errors 0 dropped 0 overruns 0 frame 0

TX packets 509 bytes 77514 (75.6 KiB)

TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

[root@0.0.0.0]#

How to download file using wget and curl command in linux ?

Download file using wget and curl command in linux

[root@0.0.0.0 ~]# rpm -qa | grep -i wget

wget-1.19.5-11.el8.x86_64

[root@0.0.0.0 ~]#

Using wget commnad :

[root@0.0.0.0 ~]#

[root@0.0.0.0 ~]# wget https://the.earth.li/~sgtatham/putty/latest/putty-0.78.tar.gz

--2023-05-22 15:44:09-- https://the.earth.li/~sgtatham/putty/latest/putty-0.78.tar.gz

Resolving the.earth.li (the.earth.li)... 93.93.131.124, 2a00:1098:86:4d:c0ff:ee:15:900d

Connecting to the.earth.li (the.earth.li)|93.93.131.124|:443... connected.

HTTP request sent, awaiting response... 302 Found

Location: https://the.earth.li/~sgtatham/putty/0.78/putty-0.78.tar.gz [following]

--2023-05-22 15:44:10-- https://the.earth.li/~sgtatham/putty/0.78/putty-0.78.tar.gz

Reusing existing connection to the.earth.li:443.

HTTP request sent, awaiting response... 200 OK

Length: 2811628 (2.7M) [application/x-gzip]

Saving to: ‘putty-0.78.tar.gz’

putty-0.78.tar.gz 100%[=====================================================>] 2.68M 4.71MB/s in 0.6s

2023-05-22 15:44:10 (4.71 MB/s) - ‘putty-0.78.tar.gz’ saved [2811628/2811628]

[root@0.0.0.0 ~]#

Using curl command :

[root@0.0.0.0 tmp]# curl -O https://the.earth.li/~sgtatham/putty/latest/putty-0.78.tar.gz

% Total % Received % Xferd Average Speed Time Time Time Current

Dload Upload Total Spent Left Speed

100 306 100 306 0 0 1066 0 --:--:-- --:--:-- --:--:-- 1066

[root@0.0.0.0 tmp]#

Friday, May 19, 2023

How to check User Shell details ?

Check User Shell details :

[root@0.0.0.0]# cat /etc/passwd

root:x:0:0:root:/root:/bin/bash

[root@0.0.0.0]# echo $0

-bash

[root@0.0.0.0]#

How to check available shell in Linux OS ?

Check available shell in Linux OS :

[root@0.0.0.0]# cat /etc/shells

/bin/sh

/bin/bash

/usr/bin/sh

/usr/bin/bash

/bin/ksh

/bin/rksh

/usr/bin/ksh

/usr/bin/rksh

[root@0.0.0.0]#

How to know Linux OS is 64 bit or 32 bit ?

First Method :

[root@0.0.0.0]#

[root@0.0.0.0]# which arch

/usr/bin/arch

[root@0.0.0.0]#

[root@0.0.0.0]# arch

x86_64

[root@0.0.0.0]#

Second Method :

[root@0.0.0.0]# uname -a

Linux ip-172-31-19-40.ec2.internal 4.18.0-425.19.2.el8_7.x86_64 #1 SMP Fri Mar 17 01:52:38 EDT 2023 x86_64 x86_64 x86_64 GNU/Linux

[root@0.0.0.0]#

Tuesday, May 23, 2023

Setup SSH Passwordless Login in Linux for oracle user

Set Timezone Using timedatectl Command in Linux

Check current time and timezone details :

option:1

[root@0.0.0.0]#

[root@0.0.0.0]#

[root@0.0.0.0]#

[root@0.0.0.0]# timedatectl status

Local time: Tue 2023-05-23 13:53:08 UTC

Universal time: Tue 2023-05-23 13:53:08 UTC

RTC time: Tue 2023-05-23 13:53:09

Time zone: UTC (UTC, +0000)

System clock synchronized: yes

NTP service: active

RTC in local TZ: no

[root@0.0.0.0]#

[root@0.0.0.0]#

Option:2

[root@0.0.0.0]#

[root@0.0.0.0]# timedatectl

Local time: Tue 2023-05-23 13:57:09 UTC

Universal time: Tue 2023-05-23 13:57:09 UTC

RTC time: Tue 2023-05-23 13:57:10

Time zone: UTC (UTC, +0000)

System clock synchronized: yes

NTP service: active

RTC in local TZ: no

[root@0.0.0.0]#

Get Timezone name using timedatectl:

[root@0.0.0.0]#

[root@0.0.0.0]# timedatectl list-timezones | grep -i kolkata

Asia/Kolkata

[root@0.0.0.0]#

Set timezone using timedatectl command :

[root@0.0.0.0]#

[root@0.0.0.0]#

[root@0.0.0.0]# timedatectl set-timezone "Asia/Kolkata"

[root@0.0.0.0]#

Validate time and timezone

[root@0.0.0.0]#

[root@0.0.0.0]# timedatectl

Local time: Tue 2023-05-23 19:28:34 IST

Universal time: Tue 2023-05-23 13:58:34 UTC

RTC time: Tue 2023-05-23 13:58:35

Time zone: Asia/Kolkata (IST, +0530)

System clock synchronized: yes

NTP service: active

RTC in local TZ: no

[root@0.0.0.0]#

[root@0.0.0.0]#

Monday, May 22, 2023

Error : -bash: ifconfig: command not found

Download file using wget and curl command in linux

Friday, May 19, 2023

Check User Shell details :

Check available shell in Linux OS :

How to know Linux OS is 64 bit or 32 bit ?

This is 64 bit Operating System because of output is x86_64