Powershell

Powershell

Windows Powershell is a shell / scripting environment created by Microsoft. You can read more about the technical stuff here. This page serves as not a complete description of Powershell or its history, but a guide on how to use it. Some programming knowledge is expected but not absolutely required. Experience with bash is also probably helpful, but you could learn something even if you have zero experience with any kind of shell or scripting environment.

Rationale

I think Powershell is pretty neat. I used Linux as my main OS for about 5 years and had to switch to Windows very recently for a myriad of reasons. Ironically I might have to switch back soon (taking a *NIX Systems Programming class), but in the meantime I wanted a scripting language for Windows that was better for the everyday grind than Python, so I did some research and found Powershell. Its no bash, but its close, and I think if it was embraced by the world and the Internet (re: people give M$ a reason to care about it) then it could be really great. The fact that Microsoft is actively trying to make Windows a more dev-friendly environment shows that exciting things are happening (See: SSH on Windows), and I believe those changes will start begin with the upcoming changes to Powershell in Windows 10.

- Anon, June 9th 2015

Getting Started =

Here is a chart that I made. File:PsQuickReference-20150609.pdf (I made it as a .pdf because I can't be assed to learn how to use WikiMedia properly, so if you don't like that please contribute yourself.) It was designed to get someone familiar with the *NIX shell up and scripting as fast as possible, and includes all the common commands I remember using often on *NIX.

Let's do a quick analysis of this chart and come up with some pros and cons.

Pros of Powershell:

• Syntax is sometimes much clearer than bash. Powershell's syntax is also much more consistent. This makes it much easier to compose and read scripts.
• Syntax is generally not case sensitive. Some people might put this as a con but I like it and I think many others do too.
• Familiar conventions to get *NIX people started, such as $ for variables, cp, mv, mkdir, etc.
• Familiar object-oriented conventions are baked in. If you come from a Java, C#, or even Ruby background, lots of things should feel familiar.
• Decently fast, both performance-wise and to learn.
• .NET environment, meaning its extensible with your own .NET objects.
• Lots of juicy default aliases for juicy shortcuts. You can tell whoever wrote this shit actually uses a shell.
• Access to lots of Windows APIs/features such as the registry and Internet Explorer.
• Powershell Community Extensions and/or PsGet.
• Its not cmd.exe ! ! !

Cons of Powershell:

• Windows only, whereas bash or sh is on basically every OS (including Windows with Cygwin).
• Cannot run scripts by default, and Powershell only comes by default with Win7 and up. Makes scripts unportable because they are not really guarunteed to run on another machine.
• Sometimes the commands are quite verbose. It can be especially annoying to type out very verbose arguments, such as '-Recurse' as opposed to '-r'.
• Fairly slow autocomplete (hopefully will be fixed in Windows 10).
• No reverse i-search by default.
• Capitals everywhere. Why? I know it usually doesn't matter but its still kind of ugly.
• Binary logs (Get-History is an example, I think).

Initial Configuration

First thing you're gonna wanna do is fix Microsoft's idiocy and make scripts executable. To do that, run this command:

   Set-ExecutionPolicy -CurrentUser RemoteSigned

You might need to do it in an elevated prompt. To do that, open the Start Menu, type 'Windows Powershell', right-click the link, and select 'Run as Administrator'. Then enter the command.

Next, you'll probably want a config file to store custom aliases, functions, and the like. To do this, run this little snippet:

   if ( -Not (Test-Path $profile)) {
       New-Item -Type File $profile
   }
   Notepad $profile

This will be where you store your customized Powershell configuration.

Some Helpful Default Aliases

Here are some useful aliases that are baked into Powershell. You'll probably find yourself using them often, and they may seem familiar, so take a good, long look.

   CommandType     Name
   -----------     ----
   Alias           % -> ForEach-Object
   Alias           % -> ForEach-Object
   Alias           ? -> Where-Object
   Alias           h -> Get-History
   Alias           r -> Invoke-History
   Alias           ac -> Add-Content
   Alias           cd -> Set-Location
   Alias           compare -> Compare-Object
   Alias           cp -> Copy-Item
   Alias           curl -> Invoke-WebRequest
   Alias           diff -> Compare-Object
   Alias           foreach -> ForEach-Object
   Alias           ft -> Format-Table
   Alias           fw -> Format-Wide
   Alias           gc -> Get-Content
   Alias           kill -> Stop-Process
   Alias           ls -> Get-ChildItem
   Alias           man -> help
   Alias           measure -> Measure-Object
   Alias           nal -> New-Alias
   Alias           nv -> New-Variable
   Alias           ps -> Get-Process
   Alias           pwd -> Get-Location
   Alias           r -> Invoke-History
   Alias           ren -> Rename-Item
   Alias           rm -> Remove-Item
   Alias           rmdir -> Remove-Item
   Alias           rv -> Remove-Variable
   Alias           sc -> Set-Content
   Alias           select -> Select-Object
   Alias           sort -> Sort-Object
   Alias           start -> Start-Process
   Alias           sv -> Set-Variable
   Alias           tee -> Tee-Object
   Alias           type -> Get-Content
   Alias           wget -> Invoke-WebRequest
   Alias           where -> Where-Object

Working with Data

Format Commands

Powershell provides several commands for changing the way that it displays data within the shell.

   PS C:\> get-command | ? { $_.Verb -eq "Format" -and $_.ModuleName -eq "Microsoft.Powershell.Utility" }
   
   CommandType     Name                                               ModuleName
   -----------     ----                                               ----------
   Cmdlet          Format-Custom                                      Microsoft.PowerShell.Utility
   Cmdlet          Format-List                                        Microsoft.PowerShell.Utility
   Cmdlet          Format-Table                                       Microsoft.PowerShell.Utility
   Cmdlet          Format-Wide                                        Microsoft.PowerShell.Utility

Format-Wide =

The most boring one: it simply puts the data in multiple columns to make better use of horizontal screen space, like so:

   PS C:\> get-process
   
   Handles  NPM(K)    PM(K)      WS(K) VM(M)   CPU(s)     Id ProcessName
   -------  ------    -----      ----- -----   ------     -- -----------
        82       7     1076       4216    44            1672 armsvc
       135       9     5800       8480    39     0.09   5320 audiodg
       316      25    15748      23808   200     6.48   2776 ConEmu
       130      11     2952       6520    91     7.09   3660 ConEmuC64
        51       6      964       4008    49     0.02   4936 conhost
        55       7     1404       4628    50     7.23   5828 conhost
       212      12     1792       3756    44             524 csrss
       180      16     2428      38256   202             600 csrss
       314      17     3880      10912    44            1728 dasHost
   ...

   PS C:\> get-process | format-wide
   
   armsvc                ConEmu
   ConEmuC64             conhost
   conhost               csrss
   csrss                 dasHost
   ....

Note that this seems to kill your use of Select-Object:

   PS C:\> ps | select-object -Property Name,ID,Handles

   Name        Id    Handles
   ----        --    -------
   armsvc    1672         82
   audiodg   5320        126
   ...

   PS C:\> ps | select-object -Property Name,ID,Handles | fw
   
   armsvc                ConEmu
   ConEmuC64             conhost
   conhost               csrss
   csrss                 dasHost
   ...

Format-List

Format-List takes an object or an array of objects and gives a descriptive output of the object's (or objects') properties and values associated with said properties. To be honest, Format-List is kind of a crappy name; the output doesn't really look like a list to me, more like a table. This command is similar to Get-Member but doesn't produce as much output and gives you the data instead of just what data members the object has.

   PS C:\> get-date
  
   Tuesday, June 9, 2015 8:58:23 PM
   
   PS C:\> get-date | format-list
   
   DisplayHint : DateTime
   Date        : 6/9/2015 12:00:00 AM
   Day         : 9
   DayOfWeek   : Tuesday
   DayOfYear   : 160
   Hour        : 20
   Kind        : Local
   Millisecond : 922
   Minute      : 58
   Month       : 6
   Second      : 27
   Ticks       : 635694803079228445
   TimeOfDay   : 20:58:27.9228445
   Year        : 2015
   DateTime    : Tuesday, June 9, 2015 8:58:27 PM