ORACLE DATABASE PROBLEM AND SOLUTIONS

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 ~]$

How to Add or Remove Linux User From Group : Linux OS

How to Add or Remove Linux User From Group ?

Add the User to a Group in Linux

[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~]#

Remove the User from a Group in Linux

[root@0.0.0.0~]#

[root@0.0.0.0~]# gpasswd -d atharv wheel

Removing user atharv from group wheel

[root@0.0.0.0~]#

[root@0.0.0.0~]# id atharv

uid=1002(atharv) gid=1002(dba) groups=1002(dba)

[root@0.0.0.0~]#

Your account has expired; please contact your system administrator : Linux OS

Re-Enable user In Linux : Your account has expired; please contact your system administrator

[atharv@0.0.0.0~]$

[atharv@0.0.0.0~]$ su - atharv

Password:

Your account has expired; please contact your system administrator

su: User account has expired

[atharv@0.0.0.0~]$

[root@0.0.0.0home]# chage -l atharv

Last password change : May 18, 2023

Password expires : never

Password inactive : never

Account expires : May 18, 2023

Minimum number of days between password change : 0

Maximum number of days between password change : 99999

Number of days of warning before password expires : 7

[root@0.0.0.0home]#

[root@0.0.0.0home]# chage --expiredate 2023-05-19 atharv

[root@0.0.0.0home]#

[root@0.0.0.0home]# chage --list atharv

Last password change : May 18, 2023

Password expires : never

Password inactive : never

Account expires : May 19, 2023

Minimum number of days between password change : 0

Maximum number of days between password change : 99999

Number of days of warning before password expires : 7

[root@0.0.0.0home]#