Let's break the following command down into its individual components

Get-EventLog -LogName Security -ComputerName REHl8SERV1, CENTOSSERV2 -Verbose

Components:

• Command: Get-EventLog
• Parameter Name 1: -LogName
  • Parameter Value 1: Security
• Parameter Name 2: -ComputerName
  • Parameter Value 2 (multiple): REHl8SERV1, CENTOSSERV2
• Parameter Name 3 (switch): -Verbose
  • Parameter Value 3: No value

You might first notice the structure of the command Get-EventLog, a verb Get followed by a single dash - and ending in a singular noun EventLog.

This structure is applicable to all native PowerShell cmdlets

After working with PowerShell for sometime you'll find you're able to intuitively construct a command you've never used before, due to all cmdlets following the same conventions. The list below contains many of the most commonly seen/used verbs:

1. Get
2. Add
3. Remove
4. New
5. Set
6. Write

So, we've discussed the base structure of a cmdlet but for those unfamiliar with scripting and development from other languages, what are parameters?

The primary function of a parameter is to provide additional input for the command to which it's attached.

Within our example: Get-EventLog -LogName Security -ComputerName REHl8SERV1, CENTOSSERV -Verbose

We have three parameters being used:

1. LogName
2. ComputerName
3. Verbose

With each being prepended by a dash -. Immediately following -LogName and -ComputerName are values being passed to provide additional context/values to these named parameters ie.

1. Single Value: Security
2. Multiple Values: REHl8SERV1, CENTOSSERV

Neither is required to be contained in quotes for this example as there are no space or punctuation marks in the values used.

The reason they are called named parameters is self-explanatory; we've explicitly named the parameters we're using. Alternatively we could use positional parameters if know what order the cmdlets expects to recieve it's arguments. Example below:

Get-EventLog Security

Only parameter -LogName is required and can be passed positionally with all other parameters being options and requiring named parameters specifying their use.

The example above will of course not provide verbose output since the -Verbose is missing and default to executing the command against localhost (The computer executing the command) since no list of external hosts is provided using -ComputerName

This concludes a brief intoduction into PowerShell. This required knowledge to learn to effectively script with PowerShell going forward.

Note you can always use Get-Help to learn more about a cmdlet's functionality and it's optional/required parameters.

Example: Get-Help -Name Get-EventLog

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