Powershell: match operator returns true but $matches is null

Strictly speaking string -match ... and collection -match ... are two different operators.The first gets a Boolean value and fills $matches.The second gets each collection item that matches a pattern and apparently does not fill $matches.

Your example should work as you expect if the file contains a single line (the first operator works).If a file contains 2+ lines then the second operator is used and $matches is not set.

The same is true for other Boolean operators applied to a collection.That is collection -op ... returns items where item -op ... is true.

Examples:

1..10 -gt 5 # 6 7 8 9 10'apple', 'banana', 'orange' -match 'e' # apple, orange 

Boolean operators applied to collections are handy if used properly.But they may be confusing as well and lead to easy to make mistakes:

$object = @(1, $null, 2, $null)# "not safe" comparison with $null, perhaps a mistakeif ($object -eq $null) {    '-eq gets @($null, $null) which is evaluated to $true by if!'}# safe comparison with $nullif ($null -eq $object) {    'this is not called'}

Another example with -match and -notmatch may look confusing:

$object = 'apple', 'banana', 'orange'if ($object -match 'e') {    'this is called'}if ($object -notmatch 'e') {    'this is also called, because "banana" is evaluated to $true by if!'}

I had the same problem, and the exact lines were working from the Powershell command prompt but not from Powershell ISE or a normal command prompt. If you don' want to cycle through all the lines of the file one by one using foreach, you can simply convert that to a string like this and it should work then:

if([string](Get-Content -path $filePath) -match $pattern){   $matches[1]}