For whatever reason it just seems impossible for any search engine to provide the correct link to download PowerShell 2 so I'm making a note of it here on my blog so that I can easily find it again:
http://connect.microsoft.com/windowsmanagement/Downloads
I wish that they'd aliased the old DOS "ver" command to Powershell's Get-Host command.
If you type "alias" at the Powershell command prompt you'll see a ton of aliases that they've setup. "dir", "copy", "cls", "compare", "md", "cd" etc. These greatly ease the transition to Powerhsell's commands if you want to quickly drop in to a command prompt and have a PowerDOS environment.
I know that I can easily configure Powershell to alias "ver" but the only time I usually need this is when I'm on a new machine and don't know what version is running. After that I don't need it anymore. Even "Get-Ver" would be more helpful and logical than Get-Host.
Anyway, if you haven't figured it out by now:
Here's a Powershell script that I've just created to remove empty folders which I'm sure I'm not going to need again in the future.
$items = Get-ChildItem -Recurse
foreach($item in $items)
{
if( $item.PSIsContainer )
{
$subitems = Get-ChildItem -Recurse -Path $item.FullName
if($subitems -eq $null)
{
"Remove item: " + $item.FullName
Remove-Item $item.FullName
}
$subitems = $null
}
}
I've been having a hard time getting Powershell's Copy-Item to work for me. My problem is that the -exclude parameter for the Copy-Item only honors the excluded items for the root directory in the destination but not for sub-directories if you also include the recurse parameter.
I believe that I have finally solved the problem with this snippet of powershell:
$source = 'd:\t1'
$dest = 'd:\t2'
$exclude = @('*.pdb','*.config')
$items = Get-ChildItem $source -Recurse -Exclude $exclude
foreach($item in $items)
{
$target = Join-Path $dest $item.FullName.Substring($source.length)
if( -not( $item.PSIsContainer -and (Test-Path($target))))
{
Copy-Item -Path $item.FullName -Destination $target
}
}
I needed to go through every file in a folder and all of its sub directories and open each file and replace a given string. This is what I finally came up with. I'm sure that this can be improved on though...
function ReplaceText($fileInfo)
{
if( $_.GetType().Name -ne 'FileInfo')
{
# i.e. reject DirectoryInfo and other types
return
}
$old = 'my old text'
$new = 'my new text'
(Get-Content $fileInfo.FullName) | % {$_ -replace $old, $new} | Set-Content -path $fileInfo.FullName
"Processed: " + $fileInfo.FullName
}
$loc = 'c:\my file\location'
cd $loc
$files = Get-ChildItem . -recurse
$files | % { ReplaceText( $_ ) }
From: Desert Code Camp 2007
Speaker: Anthony Park
Notes:
Basics:
{ - delineates a block of code.
$ - precedes a variable
-eq is 'equal'
-ne is 'not equal'
= is assignment
Store time intensive command results in a variable for later use.
e.g.: $b = Get-EventLog System
$_ is the self (this) variable.
Pipe variable or command results into the Get-Member command to see members of the object. eg: $b | Get-Member
To group a collection by one of the fields pipe the collection into the Group-Object and specify the member name as the following parameter. e.g. $b | Group-Object Source
You should sort the collection before grouping. e.g. $b | Sort-Object Source | Group-Object Source
You can filter a collection before (or after) applying the above command using the Where-Object. e.g. $b | Where-Object { $_.Source.StartsWith('S') } | Sort-Object Source | Group-Object Source
The $profile variable holds the default profile that gets run when you open Powershell. If you want to customize your Powershell then typing $profile in the Powershell environment will show you where your default profile is so that you can edit it.
To retrieve a web page into a variable try: $mypage = (New-Object Net.WebClient).DownloadString('http://guyellisrocks.com')
I've just discovered something interesting in my ventures into Powershell. If a directory has a single file in it then the Get-ChildItem in that directory will return a System.IO.FileSystemInfo object but if there are 2 or more files then it will return a System.Array object.
I'm running a script and in the script I'm getting a count of the number of files in each of several directories. So what I've found that I have to do is to check the value of the "count" member return and if it's null then I assume that the object is a System.IO.FileSystemInfo object and call the Directoy.GetFiles().count member to get the number (1) of files in there.
This is what that little snippet in my Powershell script looks like now:
$fileCollection = Get-ChildItem $s
if($fileCollection -eq $null)
{
$fileCount = 0
}
else
{
$fileCount = $fileCollection.count
}
if($fileCount -eq $null)
{
# This happens if a directory has 1 file in it. Instead of receiving an Array object back
# from the Get-ChildItem call we receive a System.IO.FileSystemInfo object and we need
# to call the Directoy.GetFiles().count on that to get the right value.
$fileCount = $fileCollection.Directory.GetFiles().count
}
$totalFileCount += $fileCount
I recently bought a book on CD and ripped it to .wma so that I could listen to it on my portable media player. When the tracks rip to disk they get named with the track number starting first. I wanted to rename the files so that the two digit disc number preceded the track number so that I could sort all of the tracks in one folder and listen to them in the correct order. Here's a Powershell script that I ran from the folder one below the ripped discs' folders.
# change directory into root of ripped files
cd "D:\Audio\Author Name"
$dirr = "BookName Disc "
$discs = 1..7 # Change to number of discs
foreach($disc in $discs)
{
$discdir = $dirr + $disc.ToString()
cd $discdir
$dir = get-childitem *.wma
foreach($x in $dir)
{
$newname = "0" + $disc.ToString() + "." + $x.Name.SubString(0,2) + ".wma"
Rename-Item $x $newname
}
cd ..
}
I've updated the code that appeared here before 8 July 2010. Previously it did not have the loop for each disc. This code still isn't perfect. Instead of prepending the 0 to the disc number when creating the new name I should be formatting the disc value.
I recently came across Scott Hanselman's Hansel Minutes and it looked like the sort of thing that I wanted to listen to. At the time I found it the archives had 109 podcasts. I wanted to download them all and stick them on my MP3 player but didn't want to click through to each link and repeat myself 109 times. I'm a big fan of the DRY principal. So I wrote a Powershell script to do it for me.
First off I examined the file naming pattern:
http://perseus.franklins.net/hanselminutes_0001.wma
to
http://perseus.franklins.net/hanselminutes_0109.wma
Fantastically simple. You couldn't ask for a nicer pattern.
So here's the script:
function main()
{
$clnt = new-object System.Net.WebClient
$sourceNames = 1..109 |%{"hanselminutes_{0:0000}.wma" -f $_}
foreach($s in $sourceNames)
{
$url = "http://perseus.franklins.net/" + $s
$target = "c:\temp\" + $s
write-host 'transfering from' $url 'to' $target
$clnt.DownloadFile($url, $target)
}
}
main
During the execution of the script over the 109 files that were in the archive at the time 3 files failed because of a timeout and 2 files failed because they didn't follow the naming pattern: The interviews with Jonathan Zuck and Robert Pickering (#'s 86 and 76 respectively) had their names tagged on to the file names.
For whatever reason I always forget the syntax to quickly find text in a bunch of source files from Powershell. Here it is so I can quickly look it up again:
Get-ChildItem -include *.cs -recurse | Select-String "string to search for"
The Get-ChildItem is the equivalent of dir in DOS.
-include is the param to tell Get-ChildItem which files to include in its search. In this case all CSharp (C#) files.
-recurse means look in subfolders under this one as well. i.e. the one that I'm running the command from.
| - this is the pipe symbol. The results of the search (a collection of files) is piped into the process that will open each file and search for the string.
Select-String - this is the command that will open a file and search for the "string to search for" string in the file. Each found line will be listed.
