PowerShell cmdlets behave similarly to Bash commands. They begin with their name and are followed by arguments and options. PowerShell cmdlets follow a verb/noun pattern.
Cmdlets begin with verbs like Get- and Set- followed by the noun that the Verb is acting on. This declarative naming approach makes reading and writing PowerShell easy to understand.
For example, the cmdlets Get-Location and Set-Location both operate on your Location in the file system. The former returns your current working directory (equivalent to pwd in Bash) while the latter changes this directory (equivalent to cd).
> Get-Location
# absolute path of your CWD
> Set-Location /path/to/destination
# changes CWD to destination path
While a bit more verbose than Bash commands, they are often more intuitive, and can read like a sentence. Every command you enter is telling the shell a statement of instructions for it to perform.
In general terms, there is a verb, a noun being acted on, and a subject.
[do] verb [to the] noun [of] subject
In the commands above, the subject is implied as the Shell process that is managing your current working directory, or Location in the file system. For example, Get-Location:
Get [the] Location [of] (this shell process)
In the Set-Location example, an additional term is added to the sentence, the path argument:
Set [the] Location [of] (this shell process) to (the path)
The analogy of commands and sentences can not be generalized to a single formula, but can be useful when learning PowerShell.
Tip
You can view the full list of built-in cmdlets and functions using the Get-Command cmdlet:
> Get-Command
# list of all built-ins available on the machine
PowerShell refers to the many types of inputs to cmdlets as parameters. As with Bash commands, some of the parameters are positional, or may even have default values. Options, or named parameters, are all written in long form (no single-letter shorthands) and use a single dash (-).
For example, the Get-Command cmdlet has a -Type option for filtering the results list by types like Cmdlet and Function:
> Get-Command -Type Cmdlet
# list of built-in cmdlets only
PowerShell cmdlets and functions allow for expansion using the tab key. This can be helpful to autocomplete command names and options. The tab key will either complete a partially written name (if it is unique) or list the possible choices.
For example, let’s explore the named parameters of Get-Command. If we enter a - (start of a named parameter) and hit tab it will show us a list of options available on Get-Command:
> Get-Command -
Name CommandType All UseAbbreviationExpansion InformationAction OutBuffer
Verb TotalCount ListImported Verbose ErrorVariable PipelineVariable
Noun Syntax ParameterName Debug WarningVariable
Module ShowCommandInfo ParameterType ErrorAction InformationVariable
FullyQualifiedModule ArgumentList UseFuzzyMatching WarningAction OutVariable
If we add a few qualifying characters, it can narrow the list down for us:
> Get-Command -Out
OutVariable OutBuffer
Whenever enough characters are available to uniquely identify a name it will autocomplete it:
> Get-Command -OutV
# after tab
> Get-Command -OutVariable
You can use this feature to automatically fill in command names, named parameters, and even paths!
While the --help option is available for some CLI tools that we will use in the class, the primary mode of viewing command documentation uses the Get-Help cmdlet.
> Get-Help <cmdlet name>
Get-Help, by default, will display the summary documentation for the given cmdlet directly in the PowerShell terminal. To view the full documentation for a cmdlet you can add the -Full option:
> Get-Help <cmdlet name> -Full
Another useful option for Get-Help is -Examples which will provide practical examples of using the cmdlet:
> Get-Help <cmdlet name> -Examples
Note
If you prefer to use the browser, using the -Online option will automatically open your browser to the full documentation:
> Get-Help <cmdlet name> -Online
PowerShell keeps commonly used documentation locally on your machine, so that it can be accessed more quickly and offline. In some cases, you will need to update your local documentation cache. You can update the local help documentation using the Update-Help cmdlet.
You can append the -Confirm option to auto-confirm the download and skip the prompt:
> Update-Help -Confirm