powershell中的-f是什么意思？

Question

I am new to powershell and trying to decode the following line from a script

Get-WmiObject -class MSFC_FCAdapterHBAAttributes -namespace “root\\WMI” | ForEach-Object {(($ .NodeWWN) | ForEach-Object {“{0:x}” -f $ })}

The script is available at: https://gallery.technet.microsoft.com/scriptcenter/Find-HBA-and-WWPN-53121140

I am more interested in the "ForEach-Object {“{0:x}” -f $_}"

what does "{0:x}" mean?

And what does the -f do to the current object $_ ?

when I run the script on my Windows Server, I see that one of the NodeWWN entry: NodeWWN : {32, 0, 0, 16...} is now converted to: 20:00:00:10:9B:17:9E:28

Would really appreciate it if the experts here could help me point out what is going on.

Answer 1

-f is the format operator , described in about_operators :

-f Format operator

Formats strings by using the format method of string objects. Enter the format string on the left side of the operator and the objects to be formatted on the right side of the operator.

 PS> "{0} {1,-10} {2:N}" -f 1,"hello",[math]::pi # 1 hello 3.14 

For more information, see the String.Format method and Composite Formatting .

The expression

<a> -f <b>

is equivalent to calling

[string]::Format(<a>, <b>)

This also means that placeholders in the format string follow the same rules as elsewhere. Normal placeholders are {0} , {1} , etc. and they can have a format for the type inserted for the placeholder, like in your example with {0:x} which would format an integer as a hexadecimal number. Predefined and custom format strings for various types in the CLR can be found in the .NET documentation , of course.

Answer 2

The -f operator takes its left argument as a description of the desired output, and its right argument as an array of values to be inserted into that string. The {0:x} specifies how to format the argument; a description can be found at SS64's page on the -f operator .

Answer 3

That makes complete sense. I tried printing out the contents of NodeWWN as is: {32, 0, 0 , 16, 155, 23, 158, 40}

With the help of the String fomrat operation where it converts from integer to Hex, I see the output 20, 0, 0, 10, 9b, 17, 9e , 28 which is the answer from my question posted initially.

Thanks a lot for helping me figure this out. Appreciate all the help!