Can the -eq function compare against a variable

Question

It appears that -eq can only compare against a literal. I am trying to compare against a variable like this. This code does not work

> $macaddr = ((getmac /v /fo csv | findstr ASIX) -split "," )[2]
> $echo $macaddr
"00-01-02-03-04-05"
> $adapter = Get-NetAdapter | ? {$_.MacAddress -eq $macaddr}
> echo $adapter
>

If I change the comparison to a literal, it appears to work fine.

> $adapter = Get-NetAdapter | ? {$_.MacAddress -eq "00-01-02-03-04-05"}
> echo $adapter
Name                      InterfaceDescription                    ifIndex Status       MacAddress             LinkSpeed
----                      --------------------                    ------- ------       ----------             ---------
Ethernet 3                ASIX AX88179 USB 3.0 to Gigabit Ethe...      12 Up           00-01-02-03-04-05       100 Mbps

How should I handle the comparison?

Answer 1

The /fo csv option makes getmac.exe quote the mac addresses, so the literal string value is not 00-01-02-03-04-05, but "00-01-02-03-04-05" (including the quotation marks), and they're obviously different:

> '00-01-02-03-04-05' -eq '"00-01-02-03-04-05"'
False

Either use ConvertFrom-Json to re-parse the output:

$macAddr = getmac /v /fo csv |ConvertFrom-Csv |Where-Object 'Network Adapter' -like '*ASIX*' |Select-Object -Expand 'Physical Address'

Or use the Trim() method to remove the quotation marks from the raw output:

$macaddr = ((getmac /v /fo csv | findstr ASIX) -split "," )[2].Trim('"')