youdidwhatwithtsql.com » Shell

More Powershell Nuggets

Rhys — Mon, 06 Jul 2009 15:47:57 +0000

In a previous post I provided a few small Powershell code blocks suitable for beginners to digest. Here are a few more that anyone starting with Powershell might like to experiment with.

A simple For Loop in Powershell

Here’s just a simple for loop in Powershell.

^?View Code POWERSHELL

# A simple for loop
for($i = 0; $i -le 10; $i++)
{
	Write-Host "Loop = $i";
}

A simple For Loop using an array in Powershell

Like all modern scripting languages, Powershell offers us an easy way to iterate over arrays.

^?View Code POWERSHELL

# Setup an array
$array = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
 
# A foreach loop using an array
foreach($item in $array)
{
	Write-Host 'Array item =' $item
}

Iterate recursively through a directory structure with Powershell

This nugget iterates through the user profile folder structure, C:\Users\Rhys on my laptop, and reports if each txt file encountered is less than 100 bytes or greater than 100 bytes.

^?View Code POWERSHELL

$dir = dir -Recurse $Env:USERPROFILE *.txt;
foreach($file in $dir)
{
	$bytes = $file.Length;
	if($bytes -lt 100)
	{
		Write-Host -ForegroundColor Green "$file < 100 bytes.";
	}
	else
	{
		Write-Host -ForegroundColor Cyan "$file >= 100 bytes.";	
	}
}

Find all .mdf and .ldf files on your C:\ drive with Powershell

These two simple lines will search through your C:\ drive looking for .mdf and .ldf files. You can easily search for different files by changing the extensions specified in the –Include switch.

^?View Code POWERSHELL

# Find all mdf and ldf files in C:\ on Local machine
$textFiles = Get-ChildItem -Path C:\ -Recurse * -Include "*.mdf", "*.ldf";
$textFiles | Format-Table -AutoSize -Property Name, Length;

Find all .mdf and .ldf files on a remote Computer with Powershell

This example is similar in function to the last one, except we’re using WMI here to query remote computers. The -ComputerName switch specifies the computer we wish to query and the -Filter switch specifies the extensions we wish to search for.

^?View Code POWERSHELL

# Find all mdf and ldf files on a remote host
$dbFiles = Get-WmiObject -Class CIM_DataFile -Filter "Extension = 'mdf' OR Extension = 'ldf'" -ComputerName "localhost";
$dbFiles | ForEach-Object { Write-Host $_.Name; }

Query Processes on local and remote Computers with Powershell

Just a few lines of code in Powershell allow you to do some pretty powerful things. Beginners should definitely check out the Get-WmiObject cmdlet and see how useful it is. The first line of code here creates an instance of the Win32_Process class. ComputerName specifies the computer you wish to query. The Filter flag contains the criteria by which we wish to filter the data. This is just like the WHERE clause in SQL. The second line simply takes the output and formats it nicely including only the columns we specify.

^?View Code POWERSHELL

$Processes = Get-WmiObject -Class Win32_Process -ComputerName 'localhost' -Filter "PageFileUsage > 0 AND Name Like '%s%'";
$Processes | Format-Table -AutoSize -Property Name, ProcessId, ThreadCount, PageFileUsage, PeakPageFileUsage, PeakVirtualSize, PeakWorkingSetSize;

Kill a Process on a remote Computer with Powershell

The script is setup to kill calc.exe on localhost but it can be changed to run for any computer, or process, that you have appropriate permissions for. To test this script make sure you have calc.exe running.

^?View Code POWERSHELL

# Kill a process on a remote machine
$computer = "localhost";
$processToKill = "calc.exe";
$process = Get-WmiObject -Class Win32_Process -Filter "Name = '$processToKill'" -ComputerName $computer;
if($process -eq $null)
{	# If null then the process may not be running
	Write-Host -ForegroundColor Red "Couldn't get process $processToKill on $computer";
	sleep(10);
	exit;
}
else
{
	Write-Host "Attempting to Kill $processToKill on $computer";
}
# Kill the process and get exit status 0 = OK
$status = $process.InvokeMethod("Terminate", $null);
switch($status)
{
	0 { Write-Host -ForegroundColor Green "Killed $processToKill on $computer"};
	default { Write-Host -ForegroundColor Red "Error, couldn't kill $processToKill on $computer"};
 
};

Post from: youdidwhatwithtsql.com

More Powershell Nuggets

Powershell Nuggets

Rhys — Wed, 22 Apr 2009 19:48:56 +0000

Here are a few Powershell nuggets for beginners to digest.

First thing that might trip you up is the Execution Policy built into Powershell. I’ve turned this off on my development machine but it’s obviously advised to have it enabled on production machines. That aside, it’s easy to turn off…

If you’re using Vista you may need to run Powershell in Administrator mode to allow the required registry change. To make my environment a little more user friendly I’ve setup a Powershell Profile with the following code

^?View Code POWERSHELL

cd C:\Users\Rhys\Documents\powershell
function prompt {"PS: $(get-date)>"}

This changes the current working directory to my scripts folder and keeps the prompt reasonably short.

Write text files with Powershell

Just look how easy it is to write text files in Powershell.

^?View Code POWERSHELL

$text = "abcdefghijklmnopqrstuvwxyz1234567890"
 
# Method 1: Write file using set-content. 
# Just pipe the contents of the variable
$text | set-content -encoding ascii alphabet.txt
 
# Method 2: Use out-file to append the for loop index to a file
for($i = 0; $i -lt 10; $i++)
{
	$i | out-file -filePath "forLoop.txt" -encoding ascii -append 
}

After executing this you should have 2 new .txt files in your working directory.

List & Count Files by Extension with Powershell

This script will list filenames and their sizes before displaying a total count of those files. Just change the extension in the script if you want to work with different file types.

^?View Code POWERSHELL

#####################################################
# Filename: DirectoryTextFiles.ps1		    #
# Author: Rhys Campbell				    #
# Description: Lists all .txt files in the current  #
# directory, with their length in bytes, and        #
# displays a total count of .txt files.		    #
# Date: 2009-04-22				    #
#####################################################
 
$count = 0;
 
$files = dir *.txt
 
foreach($file in $files)
{
	$count++;
	$filename = $file.name
	$fileLength = $file.Length 
	echo "The text file $filename is $fileLength bytes.";
}
 
echo "===================================================="
echo "Total text files in this directory = $count";

Get the Twitter Public Timeline with Powershell

One line of code is all is takes with Powershell!

^?View Code POWERSHELL

([xml](new-object net.webclient).DownloadString("http://twitter.com/statuses/public_timeline.rss")).rss.channel.item | format-table title,link

Ping multiple computers with Powershell

^?View Code POWERSHELL

###############################################
# Filename: ComputerPinger.ps1		      #
# Author: Rhys Campbell			      #
# Description: Pings multiple computers       #
# supplied in the $args array.		      #
# Date: 2009-04-16			      #
###############################################
 
# Simple ping for each computer
# supplied in the $args array
foreach($computer in $args)
{
	ping $computer;
}

Count Databases On Multiple Servers

Those of you that are still with me get to see the exciting stuff. This script will count databases, and see if SQLAGENT is running, on multiple servers. Just specify each server on the command line. This script uses Windows authentication so bear this in mind for each of your servers. It’s with examples like this that I hope you start to see the power and possibilities of Powershell.

^?View Code POWERSHELL

################################################################################
# Filename: MultiHostDatabaseCount.ps1					       #
# Description: 								       #
# Author: Rhys Campbell							       #
# Date: 2009-04-15							       #
# Usage: FullPathToFile\MultiHostDatabaseCount.ps1 server1 server2 server3 etc #
################################################################################
 
trap
{
	"Eek! An exception occured."
	write-error $("TRAPPED: " + $_.Exception.GetType().FullName);
	write-error $("TRAPPED: " + $_.Exception.Message); 
	# Terminate the script on error
	exit
}
 
# Loop through each server name supplied in the $args array
foreach($arg in $args)
{
	# Connection string
	$connectionString = "Server=$arg;Database=master;Trusted_Connection=True;"
	# setup the connection object
	$SqlConn = New-Object -Typename System.Data.SqlClient.SqlConnection
	$SqlConn.ConnectionString = $connectionString
	# Open the connection
	$SqlConn.open();
	$cmd = "SELECT COUNT(*) AS cnt FROM sys.databases";
	# Create the sql command object
	$SqlCmd = New-Object System.Data.SqlClient.SqlCommand $cmd, $SqlConn
	# Run the query
	$result = $SqlCmd.ExecuteReader()
	# Move pointer to the first row
	$result.Read() &gt; $null
	# Get db count
	$dbCount = $result[0]
	# Close the connection
	$SqlConn.close()
	# Reopen the connection
	$SqlConn.open()
	# New command to get SQLAGENT state
	$cmd = "xp_servicecontrol 'querystate', 'SQLSERVERAGENT'"
	# Create the sql command object
	$SqlCmd = New-Object System.Data.SqlClient.SqlCommand $cmd, $SqlConn
	# Run the query
	$result2 = $SqlCmd.ExecuteReader()
	# Move pointer to the first row
	$result2.Read() &gt; $null
	# Get db count
	$SQLAGENT = $result2[0]
	# Print out the database count for the host
	echo "$arg hosts $dbCount databases. The SQLAGENT Service is $SQLAGENT"
	# Clean up
	$SqlConn.close()
}

I hope to check out the huge range of Powershell Extensions and Tools available to do some really cool things. I’ve had a quick play with Quest Software’s PowerGUI. This looks pretty good but I try to stay away from fancy tools until I’ve learned the basics of a language well. I’m looking forward to working with Powershell scripting. I see some great possibilities for…

Multiple SQL Server & MySQL management. Check multiple servers in one script! Check backups, disk space, virtually anything!
Adhoc access to many data sources; including text files, rss feeds, databases, Active Directory.
Producing troubleshooting scripts for less experienced support staff.

Post from: youdidwhatwithtsql.com

Powershell Nuggets