According to Wikipedia, Windows PowerShell is Microsoft’s task automation framework, consisting of a
command-line shell and associated scripting language built on top of, and integrated with the
.NET Framework.  PowerShell can be useful when you want to see a few lines
of a very large text file.  To access PowerShell, you can click on Start, Accessories, Windows PowerShell. 
This will open a DOS-like command window.  As in Unix and DOS, you can
issue commands from the prompt.  If you do not have PowerShell installed on
your computer, you can download it from this
Microsoft
website .

The commands in PowerShell are called “cmdlets” (pronounced
“command-lets”, or small commands), and they are case-sensitive.  You can
find a listing of the available commands here
.  We will illustrate a few cmdlets that can be useful when you want to see
some of the contents of a large text file.  The lines that start with a
pound sign (#) are comments.

To get help, you can type the following cmdlets.

# getting help
# http://technet.microsoft.com/en-us/library/dd347616.aspx
get-help Get-Content -examples
man gc

We will start with the familiar “Hello, World!” to show how variables can be
created, and then using “pwd” and “dir” to get information regarding
directories.

# hello world!
$hi="Hello, World!"
$hi


pwd
dir

# counting the number of files in a folder
get-childitem D:data
get-childitem D:data -name
(get-childitem D:data).Count 

To record the script (or series of cmdlets that you type), you can use
the following cmdlets.

start-transcript "D:datatranscript.txt"
#things in between will be recorded
stop-transcript

The “Get-Content” cmdlet is very useful for accessing text files. 
In the first example, we access the first 7 rows of the text file, which we
call “large.txt”.  Next, we access the last 2 rows, and then we
get the total number of rows.  Note that the “Get-Content” cmdlet can
be shortened to “gc”.

# head
Get-Content D:datalarge.txt -totalcount 7
gc D:datalarge.txt -totalcount 7
gc D:datalarge.txt | select-object -first 7

# tail
gc D:datalarge.txt | select-object -last 2

# total number of rows
Get-Content D:datalarge.txt | Measure-Object
gc D:datalarge.txt | Measure-Object

You can access a specific column, and you can get date and time
information.

# get a specific column
# http://stackoverflow.com/questions/2503010/extracting-columns-from-text-file-using-powershell
gc D:datalarge.txt | Foreach {($_ -split 's+', 8)[7]}
gc D:datalarge.txt | Foreach {"$(($_ -split 's+', 8)[1..2])"}
gc D:datalarge.txt | Foreach {"$(($_ -split 's+', 8)[1..2])"} > col12.txt

# date and time
Get-Date
Get-Date -displayhint date
Get-Date "7/22/1980"

Below are a few examples of searching, subsetting and appending.

# searching and subsetting
more D:datalarge.txt
select-string "seqn" D:datalarge.txt 
select-string -quiet "seqn" D:datalarge.txt



# appending 
add-content -value "addthis" simple.txt
add-content -value (get-content D:datalarge.txt) simple.txt