To check how long a process has been running in PowerShell, you can use the Get-Process cmdlet and the Uptime property. The Uptime property returns the amount of time that the process has been running, in seconds.

# Get the current time

$currentTime = Get-Date

# Get the Firefox process

$firefoxProcess = Get-Process -Name firefox

# Get the start time of the Firefox process

$startTime = $firefoxProcess.StartTime

# Calculate the difference between the current time and the start time of the Firefox process

$timeRunning = $currentTime - $startTime

# Display the amount of time the Firefox process has been running

Write-Output "The Firefox process has been running for $timeRunning."

The code block above would return the following, if only 1 process of Firefox existed on this system.

The Firefox process has been running for 18:36:12.1563877.

However, it would error out if multiple processes were running, because Get-Process returns an Object. There are multiple ways this can be fixed, here are two:

$firefoxProcess = Get-Process -Name firefox | Select-Object First 1

This line could be changed to only return one result. The pipe to Select-Object, and providing the parameter, First, returns just the first item in the object. The Select-Object command has many other parameters you can read about, using: Get-Help Select-Object

Another option is the following:

# Calculate the difference between the current time and the start time of the Firefox process

$timeRunning = $currentTime - $startTime[0]

Adding the [0] allows you to iterate through an object, in this case, selecting the first item in the object.

The code example below shows both options implemented in the script from earlier.

# Get the current time

$currentTime = Get-Date

# Get the Firefox process

$firefoxProcess = Get-Process -Name firefox | Select-Object -First 1

# Get the start time of the Firefox process

$startTime = $firefoxProcess.StartTime

# Calculate the difference between the current time and the start time of the Firefox process

$timeRunning = $currentTime - $startTime[0]

# Display the amount of time the Firefox process has been running

Write-Output "The Firefox process has been running for $timeRunning."

There is a mistake in the above code block

PowerShell contains a property called Count, it returns the number of elements in an object. If there is one item only, the Count property will return 0 because there are no elements in the object, only a single object.

For example, consider the following command:

$process = Get-Process -Name firefox

This command returns a single System.Diagnostics.Process object representing the Firefox process. If you try to access the Count property of the $process object, it will return 0 because there are no elements in the object, only a single object:

$process.Count

# Output: 0

To get the number of objects returned by a command, you can use the Measure-Object cmdlet, which allows you to count the number of objects in a collection. For example:

$processes = Get-Process

$count = $processes | Measure-Object | Select-Object -ExpandProperty Count

Or alternatively, we could have declared the $process variable before setting it.

$processes = @()

$processes = Get-Process

$Processes.Count # Outputs 1

To find a file with the “.csv” extension that was last modified a year ago on the D drive using PowerShell, you can modify the -Filter parameter of the Get-ChildItem cmdlet to search for files with the “.csv” extension.

$yearAgo = (Get-Date).AddYears(-1)

Get-ChildItem -Path "D:\" -Filter "*.csv" -Recurse | Where-Object {

  $_.LastWriteTime -lt $yearAgo

}

This script uses the -Filter parameter to search for files with the “.csv” extension on the D drive, using the * wildcard to match any characters before the extension. The output of the Get-ChildItem cmdlet is then piped to the Where-Object cmdlet, which filters the results based on the last write time of the file using the LastWriteTime property. It returns only the files that were last modified before the date a year ago.

To save the result to a variable, you can use the $ symbol followed by a name for the variable. For example:

$yearAgo = (Get-Date).AddYears(-1)

$results = Get-ChildItem -Path "D:\" -Filter "*.csv" -Recurse | Where-Object {

  $_.LastWriteTime -lt $yearAgo

}

This script saves the result of the Get-ChildItem and Where-Object cmdlets to the $results variable.

To export the results to a CSV file, you can use the Export-Csv cmdlet. For example:

$yearAgo = (Get-Date).AddYears(-1)

$results = Get-ChildItem -Path "D:\" -Filter "*.csv" -Recurse | Where-Object {

  $_.LastWriteTime -lt $yearAgo

}

$results | Export-Csv -Path "C:\Temp\Results.csv" -NoTypeInformation