Making a decision (Python or PowerShell)

There are times when, as an automation engineer, we might have to choose between PowerShell and Python for certain tasks. Python is extensively used for interaction with infrastructure devices, Network Gear, and multiple vendors, but to have deep integration into and accessibility on any Windows platform, PowerShell will be the best choice. Python is extensively used in Linux environments, where PowerShell has a very limited support. PowerShell comes pre-installed in every flavor of Windows, but a major updated version (PowerShell 5.0) is available from Windows 10 onward.

PowerShell also has its own built-in libraries to support various tasks, like Python, has an extensive support community and backing from Microsoft, which adds new enhancements regularly.

Let's look at a couple of examples of PowerShell to help us understand how to write a PowerShell code.

API access

Here, we call the weather API to get coordinates for a particular location (say London, England):

#use the city of london as a reference
 $city="london"
 $urlx="https://samples.openweathermap.org/data/2.5/weather?q="+$city+"&appid=b6907d289e10d714a6e88b30761fae22"
# used to Invoke API using GET method
 $stuff = Invoke-RestMethod -Uri $urlx -Method Get
#write raw json
 $stuff
#write the output of latitude and longitude
 write-host ("Longitude: "+$stuff.coord.lon+" , "+"Latitude: "+$stuff.coord.lat)

The output is as follows:

PS C:\Users\abhishek.ratan> C:\gdrive\book2\github\edition2\chapter1\api_invoke_ps.ps1
coord : @{lon=-0.13; lat=51.51}
 weather : {@{id=300; main=Drizzle; description=light intensity drizzle; icon=09d}}
 base : stations
 main : @{temp=280.32; pressure=1012; humidity=81; temp_min=279.15; temp_max=281.15}
 visibility : 10000
 wind : @{speed=4.1; deg=80}
 clouds : @{all=90}
 dt : 1485789600
 sys : @{type=1; id=5091; message=0.0103; country=GB; sunrise=1485762037; sunset=1485794875}
 id : 2643743
 name : London
 cod : 200
Longitude: -0.13 , Latitude: 51.51

As we can see in the code, a major difference between writing code in Python and PowerShell is that in PowerShell we do not need to focus on indentation. PowerShell does not care about indentation, whereas a Python compilation would fail if strict indentation was not adhered to.

Also, we do not need to import any specific library in PowerShell, as it has very extensive built-in functions that are directly callable from the script.

Interacting with local machines

As mentioned earlier, PowerShell is deeply integrated with Windows at all levels. Let's look at an example of certain processes (system or PowerShell processes from Microsoft), running locally on the Windows machine:

Get-Process `
 | Where-Object {$_.company -like ‘*Microsoft*’}`
 | Where-Object {($_.ProcessName -like ‘*System*’) -or ($_.ProcessName -like ‘*powershell*’)}`
 | Format-Table ProcessName, Company -auto

The output is as follows (when executed from PowerShell console):

PS C:\Users\abhishek.ratan> Get-Process `
 | Where-Object {$_.company -like ‘*Microsoft*’}`
 | Where-Object {($_.ProcessName -like ‘*System*’) -or ($_.ProcessName -like ‘*powershell*’)}`
 | Format-Table ProcessName, Company -auto
ProcessName          Company
 -----------         -------
 powershell          Microsoft Corporation
 powershell_ise      Microsoft Corporation
 SystemSettings       Microsoft Corporation
 SystemSettingsBroker Microsoft Corporation

As we can see in this example, another feature of PowerShell is the piped command format support (|). Similar to Unix, a piped command in PowerShell is used to take objects, output from one cmdlet, easily send it to another cmdlet, and so on, until we granularize to a final output.

In this example, we took the output of Get-Process (which is a full process dump of our local machine), and filtered out the processes running from Microsoft Corporation. Then we further refine it to show only those processes that have the System or powershell in the name. The final output is piped to a tabular format with ProcessName and Company as the table header.