powershell select-string not working correctly

You don't get the result you expect, because Select-String doesn't output strings, but MatchInfo objects. If you pipe the output of your first Select-String into the Get-Member or Format-List cmdlet, you'll get something like this:

PS C:\> bcdedit /enum | Select-String "identifier.*current" -Context 0,3 | Get-Member   TypeName: Microsoft.PowerShell.Commands.MatchInfoName         MemberType Definition----         ---------- ----------Equals       Method     bool Equals(System.Object obj)GetHashCode  Method     int GetHashCode()GetType      Method     type GetType()RelativePath Method     string RelativePath(string directory)ToString     Method     string ToString(), string ToString(string directory)Context      Property   Microsoft.PowerShell.Commands.MatchInfoContext Context {get;set;}Filename     Property   string Filename {get;}IgnoreCase   Property   bool IgnoreCase {get;set;}Line         Property   string Line {get;set;}LineNumber   Property   int LineNumber {get;set;}Matches      Property   System.Text.RegularExpressions.Match[] Matches {get;set;}Path         Property   string Path {get;set;}Pattern      Property   string Pattern {get;set;}PS C:\> bcdedit /enum | Select-String "identifier.*current" -Context 0,3 | Format-List *IgnoreCase : TrueLineNumber : 17Line       : identifier              {current}Filename   : InputStreamPath       : InputStreamPattern    : identifier.*currentContext    : Microsoft.PowerShell.Commands.MatchInfoContextMatches    : {identifier              {current}

The Line property contains the actual matching line, and the Context property contains child properties with the pre- and post-context. Since the description line you're looking for is in the PostContext child property, you need something like this for extracting that line:

bcdedit /enum | Select-String "identifier.*current" -Context 0,3 |  Select-Object -Expand Context |  Select-Object -Expand PostContext |  Select-String 'description'

Bottom line: Select-String does work correctly. It just doesn't work the way you expect.

Select-String returns MatchInfo objects, not just the string data displayed. That data is taken from the Line and Context properties of the MatchInfo object.

Try this:

 bcdedit /enum | select-string "identifier.*current" -context 0,3 | format-list

And you'll see the various properties of the MatchInfo object.

Note that the Context property is displayed as Microsoft.PowerShell.Commands.MatchInfoContextYou'll need to drill down into this object further to get more information:

(bcdedit /enum | select-string "identifier.*current" -context 0,3).context | format-list

There you'll see that the context property is another object with PreContext and PostContext properties, where the actual Pre and PostContext lines are.

So:

(bcdedit /enum | select-string "identifier.*current" -context 0,3).Context.PostContext | Select-String 'description'

Will get the description line from the postcontext matches.

Or you can do this:

[string](bcdedit /enum | select-string "identifier.*current" -context 0,3) -split "`n" -match 'description'