Creating vSphere VM Snapshot for a given list of servers

#Taking the input from user
$File_Name = Read-Host "Provide the filename that contains the list of Servers "
$VM_list = Get-Content "$File_Name"

Write-Host "VMName`t`t`t      SnapShot Name`t`t`t`t`t    Size of Snapshot"
# Checking each Server one by one
foreach($CHK_VM in $VM_List) {
$Cap_VM_Info = Get-VM $CHK_VM | Get-Snapshot | Select VM, Name, SizeGB
$Name = $Cap_VM_Info.VM
              $SnapshotName = $Cap_VM_Info.Name
              $SizeOfSnapshot = $Cap_VM_Info.SizeGB

Write-Host "$Name`t`t$SnapshotName`t`t`t$SizeOfSnapshot"
}



Get-VM | Sort Name | Get-Snapshot | Where { $_.Name.Length -gt 0 } | Select VM,Name,Created,SizeMB

Script to scan for new disks added to a Linux server

#!/bin/bash

for channel in `ls /sys/class/scsi_host`
do
    echo "rescanning $channel"
    echo "- - -" > /sys/class/scsi_host/$channel/rescan
done

appending string after end of each line

I have a File that contains list of servers and I just want to append a domain-name (say .xyz.com ) at the end of line.

# head -5 serverlist.txt
server1
server2
server3
server4
server5
# sed  -ie 's/$/.xyz.com/' serverlist.txt
# head -5 serverlist.txt
server1.xyz.com
server2.xyz.com
server3.xyz.com
server4.xyz.com
server5.xyz.com

#

Another method using Awk:
awk '{ print $0 ".xyz.com" }' < serverlist.txt > resultfile.txt

Writing infinite loop in Perl

for (;;) {
  # perform some tasks
}

while (1) {
   # perform some tasks
}

Striping starting and trailing character of each line in a file

sed -i.backup 's/^.\(.*\).$/\1/' filename

sed -i.backup 's/^.\(.*\)".$/\1/'  filename

Useful SED Examples

Append string on each line in a given file:
# sed 's/$/<string>/'  file.txt

A sample PowerCLI script for iterating multiple vCenters

Add-PsSnapin VMware.vimAutomation.core
$vcs=@()
$vcs +="vCenter1"
$vcs +="vCenter2"
$vcs +="vCenter3"
foreach ($vc in $vcs)
{
"Connecting to $vc"
Connect-VIServer -server $vc -user xxx -password xxx
"Connected to $vc"
}
...
Disconnect-VIServer *

Some SED tips for my records

To delete trailing whitespace from end of each line:
# sed 's/[ \t]*$//' filename > filename_notrailingspace

To remove all blank lines:
# sed '/^$/d' filename > filename_noblankspace

To remove all leading and trailing whitespace from end of each line:
$ cat filename | sed 's/^[ \t]*//;s/[ \t]*$//' > filename_nospace

Perl script to check Kernel parameter differences between 2 Linux machines

This Perl script can be used for checking the Kernel Parameters difference between 2 Linux machines.

All you got to do is, take the ‘sysctl –a’ output into a file from each Linux machine that you wish to compare and give it as an input for this script like shown below:

Upon execution, you need to choose option 1 or 2.  ‘1’ is for listing out all the kernel parameter values of both servers in tabular form and ‘2’ for listing out only the parameters that are either differing or non-exist on other server.

 # perl  <scriptname>.pl  <first_server_kernel.txt>  <second_server_kernel.txt>

#!/usr/bin/perl
# Description   :       This script can be used to list out of the differences in the Kernel Settings between 2 Linux Servers.        
#                       It takes 2 files (consists of sysctl -a output) as input, upon execution it asks for User's choice either      
#                       to List out all the Kernel parameter of 2 Servers or to list out only the Differences.                        
# Version       :       1.1                                                                                                            
# Execution method :    Manual (by any normal user)                                                                                    

if( @ARGV != 2 )
{
   print "\nUsage: $0 <First-file> <Second-file>\n\n";
   print "First-file should contain 'sysctl -a' output taken from first Linux Machine\n\n";
   print "Second-file should contain 'sysctl -a' output taken from Second Linux Machine\n\n";
   exit 1;
}

open(File1, "$ARGV[0]" );
open(File2, "$ARGV[1]" );

my @first_file = <File1>;
my @second_file = <File2>;
my %output1, %output2, %kerparm;
my ($cnt1,$cnt2) = (0,0);

print "\nEnter '1' for Listing all Kernel parameters or '2' to list only the Differences : ";
my $choice=<STDIN>;
chomp($choice);

system $^O eq 'MSWin32' ? 'cls' : 'clear';
printf("%-50s %-25s %-50s\n\n", "KERNEL PARAMETER", "FIRST SERVER", "SECOND SERVER");

foreach $i(@first_file) {
        $i =~ s/\s+$//;
        @array1 = split(" = ",$i);
        $output1{$array1[0]} = $array1[1];
        $cnt1++;
        $kerparm{$array1[0]} = $cnt1;
}

foreach $j(@second_file) {
        $j =~ s/\s+$//;
        @array2 = split(" = ",$j);
        $output2{$array2[0]} = $array2[1];
        $cnt2++;
        $kerparm{$array2[0]} = $cnt2;
}

foreach $key (sort keys %kerparm)
{
  $output1{$key} = "" unless defined $output1{$key};
  $output2{$key} = "" unless defined $output2{$key};
  if($choice eq '1') {
          printf("%-50s %-25s %-50s\n", $key,$output1{$key},$output2{$key}); }
  elsif($choice eq '2') {
          printf("%-50s %-25s %-50s\n", $key,$output1{$key},$output2{$key}) if ($output1{$key} ne $output2{$key});
  }
}

PowerCLI script to get the status of CPU/Memory Hot-Plug in vSphere5

Get-VM | Get-View | Select Name, `

@{N="CpuHotAddEnabled";E={$_.Config.CpuHotAddEnabled}}, `

@{N="CpuHotRemoveEnabled";E={$_.Config.CpuHotRemoveEnabled}}, `

@{N="MemoryHotAddEnabled";E={$_.Config.MemoryHotAddEnabled}} | Export-Csv C:\<path>\file.csv