Showing posts with label PowerShell. Show all posts
Showing posts with label PowerShell. Show all posts

Friday, September 13, 2019

If you're scripting on Windows, use PowerShell

My last post on PowerShell was in 2008, so I thought I would write an update. If you're writing scripts on Windows, you should probably be using PowerShell. It seems to have 99 to 100% of the tools (especially parsers) that I ever need. I just recently needed to scrape a web page for some data, so I thought I would spend some time messing with PowerShell to get it going. Well, it only took about 30 minutes to develop the entire script that I needed, with absolutely no external dependencies.

Here's the whole script:

# get the web page. Yes, PowerShell has a 'curl' command/alias
$resp = curl -UseDefaultCredentials http://myhostname/mypagename

# Get all of the rows of the table with an ID of "serverTable"
$rows = $resp.ParsedHtml.getElementById("serverTable").getElementsByTagName("TR")

# Loop through the rows, skipping the header row: 
for ($i=1; $i -lt $rows.Length(); $i++) {

# get the hostname of this row
  $thehost = $rows[$i].getElementsByTagName("TD")[2]

# get the date this host was last rebooted
  $rebootDateString=$rows[$i].getElementsByTagName("TD")[6]

# if the host was rebooted over 20 days ago, print that date

  if ([datetime]::Now.AddDays(-20) -gt [datetime]::parseexact($rebootDateString.innerText,"G", $null))   {
    $rebootDateString.innerText } }


That's it, with no external references and nothing extra to install. It's got date parsing, date arithmetic, HTML parsing and HTTP request capabilities all built in. I realize that this then isn't portable... or is it? There's actually a PowerShell port for Linux available, with instructions here from Microsoft:


I know that Python is a hot language these days, but I don't like it as much as PowerShell. I tried to do the above with Python, and it took quite a bit longer, even though I've used Python more than PowerShell. You have to import some classes and then use XPath to find elements in the HTML. PowerShell was just straightforward and easy, at least for me, with my background and expectations. YMMV, but I like PowerShell.