LINUX AND VMWARE STUFF

Linux basics question and answer.

1. What is linux?
linux is a free open-source operating system based on unix. Linux is an alternative to the windows operating system. Linux was originally created by linus Torvalds. A student of the university of

Linux has a reputation as a very efficient and fast-performing system. Linux's kernel (the central part of the operating system) was developed by Linus Torvalds at the University of Helsinki in Finland. To complete the operating system, Torvalds and other team members made use of system components developed by members of the Free Software Foundation for the GNU Project.

2. What is OS?

 An operating system is a program that controls the execution of application programs and acts as an interface between the user of a computer and the computer Hardware. In other words “ THE SOFTWARE THAT CONTROLS THE HARDWARE “

3. What is open source operating system ?

 Open source refers to a program or software in which the source code (the form of the program when a programmer writes a program in a particular programming language) is available to the general public for use and/or modification from its original design free of charge.

4. What are the products of RedHat?

 Redhat enterprise linux, cloud computing, Redhat enterprise virtualization, etc.

5. What are different flavors (or distributions) of linux?

 Redhat, Turbolinux, Debian, Ubuntu, Fedora, OpenSUSE, Slackware, mandriva. Etc.

6. Who created unix?

 Ken Thompson in 1969.

7. Who founded open source foundation?
 The Free Software Foundation (FSF) is a nonprofit with a worldwide mission to promote computer user freedom and to defend the rights of all free software users.

8. What is the difference between rhel 4 and rhel 5 ?

difference between RHEL 4 and RHEL 5

1)In RHEL 4 SELinux Block only 13 services, But on RHEL 5 SElinux Block 80 services
2) RHEL 4 have ext2 filesystem, but RHEL 5 we have ext3 filesystem That support Journal
3)RHEL 4 have no virtualization Feature, but in RHEL 5 we have virtualization with Hypervisor-V
4)In RHEL 4 we have no Yum, But in RHEL 5 we have Yum available

( or )

XEN, YUM and improved SELinux
all the features updated with better options
Better GUI support then RHEL4
YUM over RPM package management
IPTables and SELinux for more secure environment

9. Difference bw tcp and udp ?

TCP(Transmission Control Protocol). TCP is a connection-oriented protocol, a connection can be made from client to server, and from then on any data can be sent along that connection.

a) Reliable - when you send a message along a TCP socket, you know it will get there unless the connection fails completely. If it gets lost along the way, the server will re-request the lost part. This means complete integrity, things don't get corrupted.
b) Ordered - if you send two messages along a connection, one after the other, you know the first message will get there first. You don't have to worry about data arriving in the wrong order.
c) Heavyweight - when the low level parts of the TCP "stream" arrive in the wrong order, resend requests have to be sent, and all the out of sequence parts have to be put back together, so requires a bit of work to piece together.

UDP(User Datagram Protocol). A simpler message-based connectionless protocol. With UDP you send messages(packets) across the network in chunks.

a) Unreliable - When you send a message, you don't know if it'll get there, it could get lost on the way.
b) Not ordered - If you send two messages out, you don't know what order they'll arrive in.
c) Lightweight - No ordering of messages, no tracking connections, etc. It's just fire and forget! This means it's a lot quicker, and the network card / OS have to do very little work to translate the data back from the packets.

10. what is kernel panic error ? how will you fix it if you have face it after rebooting without the the help of rescue disk ?

 Many of the Mac OSX or similar Unix like operating system users may face a type of error known as “Kernel Panic”. When this error message get displayed, you need to restart your system as your system stops working and require restart.Since the system is not in the state that you can perform the normal restart and therefore you need to force restart the computer. At that time if you were in the middle of theprocess or working with some kind of unsaved document thenit will also be lose.

The general causes of kernel panic in Mac OS X include:
a) Defective or incompatible RAM
b) Incompatible, obsolete or corrupted kernel extensions
c) Incompatible, obsolete or corrupted Drivers
d) Hard Disk corruption that include bad sectors,
e) directory corruption and other hard disk errors
f) Incorrect permissions on System files and folders
g) Less RAM or Hard Drive Memory
h) Defects in hardware, CPU or programming errors
i) Incompatible hardware

Other than these the Mac Kernel Panic occurs when the core component of Mac (kernel) gets an unexpected user instruction and fails to handle that instruction properly.

Kernel Panic Fix in Mac OS X

It is monitored that the kernel panic does not come frequently but if it’s occurred then restarting the computer will solve the problem but if the error occurs due to the corrupted/incompatible system resources then reinstall Mac OSX. When you go for the fresh installation of Mac OSX, the primary volume need to be formatted and all the data present over that volume will be lost. This condition can be a bad dream as you can lose lots of important data which you had saved on that system volume.

11. Expalin the process of kickstart installation?

a) Reboot the system
b) Press f12
c) Select second option cd-rom drive
d) Then enter the kickstart path: linux ks=nfs:192.168.0.41:/kickstart/workstation.cfg

12. There are 4 network Interfaces, how can we find which one is Primary.?
 When you type the command netstat -nr in your shell, you  will find a line starting with 0.0.0.0. Something like

0.0.0.0 192.168.0.4 0.0.0.0 UG 0 0 0 eth0

This line indicates if the system tries to contact a network outside its local network. It will first contact  the router 192.168.0.4 and it does it with the primary interface. Hence in this case its eth0. So you can check this line for the primary interface

13. Without Using $date -d yesterday. How I get the yesterday's date ?

 $date --date='yesterday'
$date --date='1 day ago'

14. why kerberos.............what its need?

Kerberos is a authentication protocol it is used to send data from one system to anohter in encrypted form.

Most conventional network systems use password-based authentication schemes. When a user needs to authenticate to a service running on a network server, they type in their password for each service that requires authentication. Their password is sent over the network, and the server verifies their identity using the password.

Transmission of passwords in plaintext using this method, while commonly done, is a tremendous security risk. Any system cracker with access to the network and a packet analyzer (also known as a packet sniffer) can intercept any passwords sent this way.

The primary design goal of Kerberos is to ensure that passwords are never sent across a network unencrypted and are preferably never sent over the network at all. The proper use of Kerberos will eradicate the threat of packet sniffers intercepting passwords on your network.

15. what is the use of nis server in linux? what is the purpose

The main purpose of NIS is centralizing the authentication database.

For ex:

Usually when a user try to login to the machine it will contact the passwd, shadow and group files for user’s  authentication, in case of user requires to access his/her account across the network we need to update users  information all these files in each machine in the network. It is bit tricky to organize multiple users’ info in all the machines in the network.

NIS server will act as central server for user authentication and all other machines will contact the NIS server for the user’s authentication info.
Make sure all the machines in your network should be in the same domain. NIS will work only in single domain.

16. How many minimum partitions need to install the linux?

Two minimum partition need to install the linux

1: /boot
2: /

SWAP is not mendatary to create at the time of installation it is only use for Virtual Memory purpose.... as you required when u create...


17. how is FAT32 file system mounted in linux file system?

1: mkdir /kaka
2: open vim /etc/fstab and mount it permently.
3: mount -t vfat /dev/hda1 /kaka
4: /dev/hda1...... drive name.


18. Major difference between SMB and NFS ?

 main difference between samba and nfs is - By configuring samba we can access fileS from linux to window and window to linux but by nfs can't

19. Major difference between RPM and YUM ?

the main difference of rpm and yum is that yum will install all the package including dependencies if it is present in the server. but in rpm we have to install each and every dependency ourself.

20. Command to check last runlevelwho -r


21. Is it possible to give access to a nfs share to a particular user in a particular system?

you can give permission to an ip or to the users(The usershould be from the system where the file is gettingshared,external access from users arenot allowedexcept fornfsnobody). If you want to give permission to an ip then open /etc/exports...Let /data be the shared directory: /data 10.2.1.1(ro,sync)

To give permission to a user like harry: setfacl -m u:harry:rwx /data.

By default the nfs gets accessed by the user nfsnobody. So you can add or remove a particular permissions to this user using acl.

22. In Linux OS, what is the file server?

NFS (Network File System) is the File server in Linux. We can also use the LDAP (Lightweight Direct Access Protocol)for the File server. NFS is easy to configure than LDAP. For NFS, we need the dameon portmap,nfsd etc../etc/exports is a file contains the partitions, which we want to share. NIS server which should configure for clients. we need ypbind,netfs services in clients


23.  Explain cups in linux.

 It is printer deamon

C - common
U - Unix
P - printing
S - system

24. what are pipes ? explain use of pipes ?

 a pipe is a chain of processes so that output of one process(stdoutput) is fed an input(stdinput) to another process.


25. What is the minimum number of partitions you need to install Linux?

Minimum 2 partitions are needed for installing Linux. 
The one is / or root which contains all the files and the other is swap. Linux file system is function specific which means that files and folders are organized according to their functionality. For example, all executables are in one folder, all devices in another, all libraries in another and so on. / or ‘root’ is the base of this file system. All the other folders are under this one. / can be consider as C: .Swap is a partition that will be used as virtual memory. If there is no more available RAM a Linux computer will use an area of the hard disk, called swap, to temporarily store data. In other words it is a way of expanding your computers RAM.

26. Which command is used to review boot messages?

dmesg command is used to review boot messages. This command will display system messages contained in the kernel ring buffer. We can use this command immediately after booting to see boot messages. A ring buffer is a buffer of fixed size for which any new data added to it overwrites the oldest data in it. Its basic syntax is

dmesg [options]

Invoking dmesg without any of its options causes it to write all the kernel messages to standard output. This usually produces far too many lines to fit into the display screen all at once, and thus only the final messages are visible. However, the output can be redirected to the less command through the use of a pipe, thereby allowing the startup messages to be viewed on one screen at a time
dmesg | less

27. What are the partitions created on the mail server hard drive?

The main partitions are done firstly which are root, swap and boot partition. But for the mail server three different partitions are also done which are as follows:
1. /var/spool- This is done so that if something goes wrong with the mail server or spool than the output cannot overrun the file system.
2. /tmp- putting this on its own partition prevents any user item or software from overrunning the system files.
3. /home- putting this on its own is useful for system upgrades or reinstalls. It allow not to wipe off the /home hierarchy along with other areas.

28. Which daemon is responsible for tracking events on Linux system?

syslogd is responsible for tracking system information and save it to the desired log files. It provides two system utilities which provide system logging and kernel message trapping.

29. Which daemon is used for scheduling of the commands?

The crontab command is used for scheduling of the commands to run at a later time. SYNTAX
crontab [ -u user ] file
crontab [ -u user ] { -l | -r | -e }

Options
-l List - display the current crontab entries.
-r Remove the current crontab.
-e Edit the current crontab using the editor specified by the VISUAL or EDITOR environment variables.

30. how to recollect root password?

a) go to single user mode
b) type passwd and then the required password u want to change
c) if it gives u error on entering the passwd command
d) than type setenforce 0 it will disable the selinux for that moment and than again type the passwd command to change the password


31. what is LILO?

LILO stands for Linux boot loader. It will load the MBR, master boot record, into the memory, which tell the system which partition and hard drive to boot.

32. What is the difference between Telnet and SSH?

ssh is a secured shell, where telnet is not a secured one.when you ssh to trasnfer data between a system, the data will be send in the encrypted form, where the hacker cannot encode or decode it.

While you telnet,the data send between the system is alphabetical format(ASCII), where every one can understand. More over as per network security, telnet and ftp are prohibited. Always, trust SSL based data transfer.

33. User unable to login in server then how can u troubleshooting it? Example: server at Atlantic-DC. in that server two users try to login in server. 1st user able to login. but second user unable to login so how can troubleshoot it ?
Passwd expired r not

# usermod -l username

2)User is locked r not using the command

# passwd -u username -to unlock the user

3)passwd file problem

if any change in /etc/passwd file r /etc/shadow file

4)change the passwd

#passwd

5)The default permission for security file is 600 when the value is changed,we can't login

#ls -ld /etc/secur


34. Explain linux file types?

7 types of files

- regular
d directory
l symbolic link
c character special file (hardware files)
b block special file (files to communicate with hardware)
p named pipe (to pass data between process )
s socket ( mechanism for inter-process communication

35. Please explain the file structure of linux?
The Linux system contains thousand of files located within many directories. All directories are organized in a tree-structure like manner.
* The 'trunk' of the tree is the root directory.
* The root directory is simply identified as a "/".
* All other directories 'branch' off from the trunk.

The following lists the most common directories and their intended contents.

* / - root directory
* /home - where directories are contained for each user,
example:
* /usr - pronounced 'user' and contains Linux commands and utilities
o /bin - binary executable programs
o /lib - program libraries, similar to Windows 'dll' files
o /sbin - more executable programs and Linux utilities for administrative purposes
o /doc - documentation
o /src - source code to programs
* /tmp - temporary work files
* /etc - configuration files
o /rc.d - scripts used during boot and shutdown process
o /sysconfig - default configuration files
o /sysconfig/network-scripts - network scripts
o /sysconfig/daemons - special programs that run in background, such as print spooling
* /bin - binary executable programs that all users need
* /dev - device files that control drives, terminals andany equipment attached to the server
* /var - user specific files
o /log - log files containing system usage and errors
o /spool - where spooled files are stored during print spooling process
o /mail - where Email files are stored until retrieved by client Email program
* /proc - system files
* /root - root's home directory
* /opt - other options
* /sbin - more executable programs and utilities


36. Can we open pdf files in suse?

We can open .pdf file with the help of CUPS-PDF package.
Install CUPS-PDF package and use pdf file.

37. Why you shouldn’t use the root login?

Root has full control over the system Its like Admin.There ll be full credentials for root.If deleted any datas as root login its difficult to recover.

38. Who owns data dictionary?

The SYS user owns the data dictionary. The SYS and SYSTEM users are created when the database is created.

1. Command to list the files in a directory?

ls - list directory contents
ls -l (-l use a long listing format)

2. Command to list all the files in a directory, including the hidden files?

ls -a (-a, do not hide entries starting with .)

3. Command to find out all processes that are currently running?

 ps -f (-f does full-format listing.)

4. Command to find out the processes that are currently running or a particular user?

ps -au Myname (-u by effective user ID (supports names)) (a - all users)

5. Command to kill a particular process?

kill -9 23456 (process_id 23456) or kill -9 %8765 (job number 8765)
kill -9 -1 (Kill all processes you can kill.)
killall - kill processes by name most (useful - killall java)


6. Commands to view the contents of the file?

less filename
cat filename
more filename   
tail filename       -  can see the end of the file.
head filename    - can see the head of the file
vi filename
vim filename


7. Commands to use edit contents of the file?

vi  filename
vim  filename
nano filename
view  filename
visudo — edit the sudoers file

8. Command to view contents of a large log file?

tailf /var/log/messages ( last 10 rows)
less filename
head /var/log/messages  (first 10 rows)

9. How do you log in to a remote Unix box?

ssh  remote_server — OpenSSH SSH client (remote login program)


10.How do you get help on a UNIX terminal?

man command_name
info command_name (more information)

11.Command to list contents of a directory including all of its
subdirectories, providing full details and sorted by modification time?
ls -acl  filename
-a    all entries
-c    by time
-l     use a long listing format

12.How do you create a symbolic link to a file (give some reasons of doing so)?

ln - make links between files

Links create pointers to the actual files, without duplicating the contents of
the files. That is, a link is a way of providing another name to the same file.
There are two types of links to a file.

a.Hard link
b.Symbolic (or soft) link

13. What is a filesystem?

Sum of all directories called file system.
A file system is the primary means of file storage in UNIX.
File systems are made of inodes and superblocks.

14. Command to get file system usage?

df - report file system disk space usage.

15. How do you check the sizes of all users home directories (one command)?

du -sh /home/

du command summarize disk usage of each FILE, recursively for directories.. 

We have 2 types of mode we can configure the multipath.

Redundancy

DM-Multipath can provide failover in an active/passive configuration. In an active/passive configuration, only half the paths are used at any time for I/O. If any element of an I/O path (the cable, switch, or controller) fails, DM-Multipath switches to an alternate path.

Improved Performance

DM-Multipath can be configured in active/active mode, where I/O is spread over the paths in a round-robin fashion. In some configurations, DM-Multipath can detect loading on the I/O paths and dynamically re-balance the load.

Powercli Code to Consolidate all  vms  which are Consolidation Needed

Use the below command.

Get-VM |
Where-Object {$_.Extensiondata.Runtime.ConsolidationNeeded} |
ForEach-Object {
  $_.ExtensionData.ConsolidateVMDisks()
}

change the Lockdown Mode on all hosts managed by vCenter

Follow the below steps to achieve the requirement:

$vCenter = 'vCenterServer_Name_or_IP_address'
Connect-VIServer $vCenter
 $Scope = Get-VMHost #This will change the Lockdown Mode on all hosts managed by vCenter, amend this if you need to foreach ($ESXhost in $Scope) {
 (get-vmhost $ESXhost | get-view).ExitLockdownMode() # To DISABLE Lockdown Mode
 # (get-vmhost $ESXhost | get-view).EnterLockdownMode() # To ENABLE Lockdown Mode
 }
Disconnect-VIServer -Server $vCenter -Confirm:$false

Repairing Linux ext2 or ext3 file system

1) File system must be unmounted, you cannot repair it while it is running. Take system down to runlevel one (make sure you run all command as root user):# init 1

2)Unmount file system, for example if it is /home (/dev/sda3) file system then type command

# umount /home OR# umount /dev/sda3

3) Now run fsck on the partition: 
# fsck /dev/sda3

However be sure to specify the file system type using -t option. Recenly one of our sys admin run the command on ext3 file system w/o specifying file system. Result was more corruption as fsck by default assumes ext2 file system.

 # fsck -t ext3 /dev/sda3
OR# fsck.ext3 /dev/sda3

Tip if you don't know your file system type then typing mount command will display file system type.

fsck will check the file system and ask which problems should be fixed or corrected. If you don't wanna type y every time then you can use pass -y option to fsck


# fsck -y /dev/sda3

Please not if any files are recovered then they are placed in /home/lost+found directory by fsck command.

4) Once fsck finished, remount the file system:
# mount /home

5) Go to multiuser mode# init 3

Read man page of fsck for more.

Run the below tcpdump command on physical server.

[root@testserver001 ~]# tcpdump -nn -v -i eth0 -s 1500 -c 1 'ether[20:2] == 0x2000'
tcpdump: WARNING: eth0: no IPv4 address assigned
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 1500 bytes
05:51:39.526913 CDPv2, ttl: 180s, checksum: 692 (unverified), length 434
        Device-ID (0x01), length: 21 bytes: 'TEST01.switch.com'
        Version String (0x05), length: 295 bytes:
          Cisco Internetwork Operating System Software
          IOS (tm) s72033_rp Software (s72033_rp-ADVIPSERVICESK9_WAN-M), Version 12.2(18)SXF17a, RELEASE SOFTWARE (fc1)
          Technical Support: http://www.cisco.com/techsupport
          Copyright (c) 1986-2010 by cisco Systems, Inc.
          Compiled Tue 02-Mar-10 01:50 by tinhuang
        Platform (0x06), length: 16 bytes: 'cisco WS-C6506-E'
        Address (0x02), length: 13 bytes: IPv4 (1) 159.166.128.131
        Port-ID (0x03), length: 16 bytes: 'FastEthernet3/12'
        Capability (0x04), length: 4 bytes: (0x00000029): Router, L2 Switch, IGMP snooping
        VTP Management Domain (0x09), length: 0 byte: ''
1 packets captured
3 packets received by filter
0 packets dropped by kernel

Windows PowerShell (SCVMM)

SCVMM One-liner command 1:   Outputs the VMName, VM Configuration File path, VHDCount, VHD Location, VHDSize, MaxVHDSize, Cluster for all VMs managed by the SCVMM server connected by PowerShell (in a single line)

$report = @(); $vms = get-vm; foreach ($vm in $vms){foreach ($vhd in $vm.VirtualHardDisks){$maxvhdsize = [math]::Round($vhd.MaximumSize/1024/1024/1024,1); $vhdsize = [math]::Round($vhd.Size/1024/1024/1024,1); $row = "" | select VMName, VMCPath, VHDCount, VHDLocation, VHDSize, MaxVHDSize, VMCluster; $row.VMName = $vm.Name; $row.VMCPath = $vm.VMCPath; $row.VHDCount = $vm.VirtualHardDisks.Count; $row.VHDLocation = $vhd.Location; $row.VHDSize = $vhdSize; $row.MaxVHDSIze = $MaxVHDSize; $row.VMCluster = $vm.VMHost.HostCluster.Name; $report += $row;};};$report | export-csv C:\Temp\Hyper-V-VMs.csv -NoTypeInformation

What are custom attributes?

Custom Attributes are attributes that a administrator can define for all Virtual Machines and Hosts in vCenter. The attributes are then displayed in the “Annotations” box for each VM. The custom attributes are also displayed alongside the VM Name, Status, State, CPU Usage, etc, when listing virtual machines in the Datacenter, cluster, host, and resource pool views.

Why use them?

Daily, we receive lots of clone requests for VMs. Clones are very good for application development and application troubleshooting. When an application on a VM goes pear shaped, the application vendor may request a clone for a system. They can then work on the clone system to try and fix some issues while the production system (if not broken completely) may in some cases still remain partially available to the end users. Once they are confident that they have resolved the issue, they can then implement the fix in the production environment.

This is all good and well, but here’s the problem. Clones are a drain on your resources. As administrator, you should be very careful to simply hand out clones as the requests come in. Virtual Machine clones can create a nightmare for administrators as they use huge amounts of additional disk space. Some of the clones we have today are in excess of 420GB. When creating clones, we need to make sure that the following information is recorded somewhere in vCenter:

·         Who requested the clone;

·         The requestor’s contact number/email address

·         The date that the clone was made;

·         The size of the clone on disk (all vDisk sizes combined + the amount of RAM  assigned to the VM);

·         Does it need to be backed up (Yes / No);

·         Reason for the clone;

Specifying your own Custom Attributes

Creating custom attributes is very simple. In the VI (or vSphere) client on the menu bar, click “Administration” >> “Custom Attributes...”

You’ll now be presented with the Custom Attributes dialog: You can file them b editing them manually once created.

VMware Technical Support routinely requests diagnostic information from you when a support request is handled. This diagnostic information contains product specific logs, configuration files, and data appropriate to the situation. The information is gathered using a specific script or tool for each product and can include a host support bundle from the ESXi host and vCenter Server support bundle. Data collected in a host support bundle may be considered sensitive.




 #Variable declaration
$vCenterIPorFQDN="VCName"
$vCenterUsername="domain\user" #Any User name who has access to Vcenter.
$vCenterPassword="xxxx"
$destination ="C:\Users\user\Desktop\naga\" #Location where to download support bundles
 
Write-Host "Connecting to vCenter" -foregroundcolor "magenta"
Connect-VIServer -Server $vCenterIPorFQDN -User $vCenterUsername -Password $vCenterPassword
 
$hosts = Get-VMHost #Retrieve all hosts from vCenter
 
Write-Host "Downloading vCenter support bundle" -foregroundcolor "magenta"
Get-Log -Bundle -DestinationPath $destination
 
foreach ($esxihost in $hosts){
Write-Host "Downloading support bundle for ESXi host $($esxihost.Name)" -foregroundcolor "magenta"
Get-Log -VMHost (Get-VMHost -Name $esxihost.Name) -Bundle -DestinationPath $destination
}

These instructions describe the steps required to clone an LVM2 volume
group by creating a duplicate copy of the physical storage (PVs). This
requires the VG be deactivated while the clone is created and
re-named.

The volume group being cloned, CloneVG consists of two PVs originally present
on /dev/testpv0 and /dev/testpv1. A new volume group named CloneVG-clone will
be created on devices /dev/testpv2 and /dev/testpv3.

1. Deactivate the VG

       # vgchange -an CloneVG

2. Create the cloned PV(s)

       E.g., dd, clone LUNs on storage, break mirror etc.

       # dd if=/dev/testpv0 of=/dev/testpv2
       # dd if=/dev/testpv1 of=/dev/testpv3

3. For each original PV, create a filter entry in /etc/lvm/lvm.conf to
temporarily mask the PV from the LVM tools.

Preserve a copy of the original filtering rules so that it can be
restored at the end of the process, for example:

       # cp /etc/lvm/lvm.conf /etc/lvm/lvm.conf.orig

To exclude the original loopback devices /dev/testpv0 and /dev/testpv1, the
filter line could look like this:

       filter = [ "r|/dev/testpv0|", "r|/dev/testpv1|", "a|.*|" ]

Or, using a regex to match both devices with a single rule:

       filter = [ "r|/dev/loop[01]|", "a|.*|" ]

Once the filters are set up, remove the LVM persistent cache:

       # rm -f /etc/lvm/.cache [versions before 2.02.23]
OR
       # rm -f /etc/lvm/cache/.cache [version 2.02.23 or later]

Verify that the filtering is correct by running pvscan:

       # pvscan
         PV /dev/testpv2   VG CloneVG         lvm2 [60.00 MB / 40.00 MB free]
         PV /dev/testpv3   VG CloneVG         lvm2 [60.00 MB / 40.00 MB free]
         Total: 2 [120.00 MB] / in use: 2 [120.00 MB] / in no VG: 0 [0   ]

Only the cloned PVs should be displayed. If the original PVs appear,
check the syntax of the filtering rule and clear the persistent cache
again.

4. Modify the cloned volume group name, ID and physical volume IDs to
avoid name and UUID clashes between the original and cloned devices:

For each cloned physical volume, run:

       # pvchange --uuid /path/to/physical/volume

This will generate a new random UUID for the specified physical volume
and update the volume group metadata to reflect the changed identity.

For example:

       # pvchange --uuid /dev/testpv2
         Physical volume "/dev/testpv2" changed
         1 physical volume changed / 0 physical volumes not changed
       # pvchange --uuid /dev/testpv3
         Physical volume "/dev/testpv3" changed
         1 physical volume changed / 0 physical volumes not changed

Generate a new UUID for the entire volume group using vgchange:

       # vgchange --uuid CloneVG
         Volume group "CloneVG" successfully changed

Finally, rename the cloned VG:

       # vgrename CloneVG CloneVG-clone

5. Remove filtering rules & verify both VGs co-exist correctly

Restore the original filtering configuration and wipe the persistent cache:

       # cp /etc/lvm/lvm.conf.orig /etc/lvm/lvm.conf
       cp: overwrite `/etc/lvm/lvm.conf'? y
       # rm -f /etc/lvm/.cache

Run pvscan to verify the new and old VGs are correctly displayed:

       # pvscan
         PV /dev/testpv0   VG CloneVG         lvm2 [60.00 MB / 40.00 MB free]
         PV /dev/testpv1   VG CloneVG         lvm2 [60.00 MB / 40.00 MB free]

         PV /dev/testpv2   VG CloneVG-clone   lvm2 [60.00 MB / 40.00 MB free]
         PV /dev/testpv3   VG CloneVG-clone   lvm2 [60.00 MB / 40.00 MB free]
         Total: 4 [240.00 MB] / in use: 4 [240.00 MB] / in no VG: 0 [0  ]

6. Activate volume groups

Both the original and cloned VGs can now be activated simultaneously:

       # vgchange -ay CloneVG
         1 logical volume(s) in volume group "CloneVG" now active

       # vgchange -ay CloneVG-clone
         1 logical volume(s) in volume group "CloneVG-clone" now active

To allow  all users to set-up password-less sudo
Edit the visudo file by simply typing

ALL     ALL = (ALL) NOPASSWD: ALL

to allow all users to run all commands without a password.
Add the following line for a user called username alone  to setup password-less sudo

username ALL=(ALL) NOPASSWD: ALL

Add the following line for a group called wheel to set-up password-less sudo

# %wheel        ALL=(ALL)       NOPASSWD: ALL