ORACLE DATABASE PROBLEM AND SOLUTIONS

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]#

This is 64 bit Operating System because of output is x86_64

Thursday, May 18, 2023

How to get metadata details for AWS EC2 instance using curl command

Get metadata details for AWS EC2 instance using curl command

[root@]# curl http://169.254.169.254/2018-09-24/meta-data

ami-id

ami-launch-index

ami-manifest-path

block-device-mapping/

events/

hibernation/

hostname

identity-credentials/

instance-action

instance-id

instance-type

local-hostname

local-ipv4

mac

metrics/

network/

placement/

profile

public-hostname

public-ipv4

public-keys/

reservation-id

security-groups

services

Example:

[root@]# curl http://169.254.169.254/2018-09-24/meta-data/security-groups

kpitdb-demo-db-sg

Adding Users to Sudoers in Linux

Login as root user : visudo and check wheel (group) details should be there

## Sudoers allows particular users to run various commands as

## the root user, without needing the root password.

## Examples are provided at the bottom of the file for collections

## of related commands, which can then be delegated out to particular

## users or groups.

## This file must be edited with the 'visudo' command.

## Allows people in group wheel to run all commands

%wheel ALL=(ALL) ALL

## Same thing without a password

# %wheel ALL=(ALL) NOPASSWD: ALL

Login as root user to add user (atharv) in wheel group (sudoers)

[root@0.0.0.0~]# usermod -aG wheel atharv

[root@0.0.0.0~]#

[root@0.0.0.0~]# id atharv

uid=1002(atharv) gid=1002(dba) groups=1002(dba),10(wheel)

[root@0.0.0.0~]#

Login as atharv user

[atharv@0.0.0.0 ~]$ su - atharv

Password:

Last login: Thu May 18 11:50:13 UTC 2023 on pts/1

[atharv@0.0.0.0 ~]$

[atharv@0.0.0.0 ~]$ sudo fdisk -l

Disk /dev/xvda: 60 GiB, 64424509440 bytes, 125829120 sectors

Units: sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disklabel type: gpt

Disk identifier: 2E431796-24CD-41A3-A4CB-7987FFF67072

Device Start End Sectors Size Type

/dev/xvda1 2048 4095 2048 1M BIOS boot

/dev/xvda2 4096 125829086 125824991 60G Linux filesystem

[atharv@0.0.0.0 ~]$

[atharv@0.0.0.0 ~]$ sudo ls -la /root

total 260816

dr-xr-x---. 9 root root 4096 May 18 11:12 .

dr-xr-xr-x. 21 root root 4096 Jan 13 14:03 ..

-rw-------. 1 root root 6953 May 4 2021 anaconda-ks.cfg

drwx------ 4 root root 27 Apr 14 10:20 .ansible

drwxr-xr-x 3 root root 22 Apr 14 10:14 ansible

-rw-r--r-- 1 root root 77218345 Jan 9 18:30 'AutoDL?BundleId=247937_0ae14417abb444ebb02b9815e2103550'

-rw-r--r-- 1 root root 137320 Feb 18 13:07 aws_replication_agent_installer.log

-rw-r--r-- 1 root root 25289 Feb 6 10:25 aws-replication-installer-init.py

-rw-------. 1 root root 17257 May 18 11:12 .bash_history

-rw-r--r--. 1 root root 18 Aug 12 2018 .bash_logout

-rw-r--r--. 1 root root 176 Aug 12 2018 .bash_profile

-rw-r--r--. 1 root root 176 Aug 12 2018 .bashrc

drwx------ 3 root root 20 Sep 21 2022 .config

drwxr-xr-x 6 root root 95 Sep 21 2022 .cpan

drwxr-xr-x 3 root root 55 Sep 21 2022 .cpanm

-rw-r--r--. 1 root root 100 Aug 12 2018 .cshrc

-rw-r--r-- 1 root root 189609546 Dec 7 23:14 jdk-19_linux-x64_bin.rpm

drwxr-xr-x 3 root root 105 Feb 18 13:01 mgn18022023

-rw-------. 1 root root 0 May 16 17:02 original-ks.cfg

-rw------- 1 root root 3167 Nov 8 2022 .psql_history

drwx------. 2 root root 48 Apr 14 10:25 .ssh

-rw-r--r--. 1 root root 129 Aug 12 2018 .tcshrc

-rw-r--r-- 1 root root 111 May 18 10:44 test.txt

-rw------- 1 root root 1047 May 18 08:41 .viminfo

-rw------- 1 root root 518 May 18 05:50 .Xauthority

[atharv@0.0.0.0 ~]$