Posted on Monday February 15, 2016

Powershell - the good parts

I’ve been using Powershell on a daily basis for about 2 years now, mostly with Chocolatey and provisioning servers (the devops movement). Whilst it’s a huge improvement over batch files (anything is) and VBS, it is has foibles.

Infact it has so many foibles I would put it firmly in the languages-with-very-strange-design-decisions category reserved for Javascript and Perl:

  • The “number 1” stinker: the .ps1 and .psm1 file extensions. Did they think Powershell was only going to have one version?
  • The same applies for the profile folder, it lived until recently inside Powershell1. Oh and there’s also 6 different profile locations.
  • $true and $false as constants
  • $HOME vs ~ vs $env:HOME (explaination here)
  • Error handling. Do we try {} catch, -ErrorAction, $ErrorActionPreference, 2>&1, $LastExistCode? I know there is a distinct difference between the four but it doesn’t make it any less nutty.
  • Help docs. If I want help on a cmdlet I have to use get-help invoke-webrequest or the shortcut man wget, not just -help
  • …which leads onto unix shortcuts. They’re not unix shortcuts as they’re different commands with completely different syntaxes. For example wget, curl, ls.
  • Functions. You declare them with brackets, you call them without.

These are more minor quibbles:

  • Inconsistently with semi colons at the end of the lines.
  • Casting is a complete beast.
  • String lookups/replacements are also not nice if you’re not familiar with the .NET framework.
  • No easy way to log output, even with the transcript commands.
  • A separate metadata file for modules - why not just use YAML (frontmatter) at the top or bottom of the file?
  • -eq -neq -gt. But there is actually a design decision behind this that makes sense, based on dash command line argument seperator and having to maintain the > as a pipe.

That sounds like a damning critique but really the only two features that get annoying on a daily basis are the error handling and the help. The shortcomings are in some ways countered by the good parts:

  • Really easy to pickup if you’re from a .NET background.
  • A familar Perl/PHP-like syntax for the variables and comments.
  • You can use the .NET framework fairly easily: C:\>[System.DateTime]::Now (there’s a shortcut: get-date)
  • You can alias commands easily
  • Modules are easy to write.
  • The CLI intellisense in Windows 10 is nice.
  • The language is updated regularly, it’s not left to fester like batch.
  • Chocolately and Boxstarter simplify a large portion of what you do.

If you need to write infrastructure as code for Windows you’re a bit stuck as the alternatives to Powershell aren’t any better, they either lack the libraries Powershell has, or need to be compiled and aren’t familiar to cross-platform sys-ops. So for now I’m happy with Powershell but do enjoy a good British moan at it every so often.