Powershell - Regular Expression Multiple Matches

Question

Maybe my reasoning is faulty, but I can't get this working.

Here's my regex: (Device\s#\d(\n.*)*?(?=\n\s*Device\s#|\Z))

Try it: http://regex101.com/r/jQ6uC8/6

$getdevice is the input string. I'm getting this string from the Stream/Output from a command line tool.

$dstate = $getdevice |
     select-string -pattern '(Device\s#\d(\n.*)*?(?=\n\s*SSD\s+|\Z))' -AllMatches |
     % { $_ -match '(Device\s#\d(\n.*)*?(?=\n\s*SSD\s+|\Z))' > $null; $matches[0] }
Write-Host $dstate

Output:

Device #0 Device #1 Device #2 Device #3 Device #4

Same output for the $matches[1], $matches[2] is empty.

Is there a way I can get all matches, like on regex101.com? I'm trying to split the Output/String into separate variables (one for Device0, one for Device1, Device2, and so on).

Update: Here's the Output from the command line tool: http://pastebin.com/BaywGtFE

Answer 1

I used your sample data in a here-string for my testing. This should work although it can depend on where your sample data comes from.

Using powershell 3.0 I have the following

$getdevice | 
    select-string -pattern '(?smi)(Device\s#\d+?(.*?)*?(?=Device\s#|\Z))' -AllMatches | 
    ForEach-Object {$_.Matches} | 
    ForEach-Object {$_.Value}

or if your PowerShell Verison supports it...

($getdevice | select-string -pattern '(?smi)(Device\s#\d+?(.*?)*?(?=Device\s#|\Z))' -AllMatches).Matches.Value

Which returns 4 objects with their device id's. I don't know if you wanted those or not but the regex can be modified with lookarounds if you don't need those. I updated the regex to account for device id with more that one digit as well in case that happens.

The modifiers that I used

1. s modifier: single line. Dot matches newline characters
2. m modifier: multi-line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
3. i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])

Another regex pattern thats works in this way that is shorter

'(?smi)(Device\s#).*?(?=Device\s#|\Z)'

Answer 2

With your existing regex, to get a list of all matches in a string, use one of these options:

Option 1

$regex = [regex] '(Device\s#\d(\n.*)*?(?=\n\s*Device\s#|\Z))'
$allmatches = $regex.Matches($yourString);
if ($allmatches.Count > 0) {
    # Get the individual matches with $allmatches.Item[]
} else {
    # Nah, no match
} 

Option 2

$resultlist = new-object System.Collections.Specialized.StringCollection
$regex = [regex] '(Device\s#\d(\n.*)*?(?=\n\s*Device\s#|\Z))'
$match = $regex.Match($yourString)
while ($match.Success) {
    $resultlist.Add($match.Value) | out-null
    $match = $match.NextMatch()
} 

Answer 3

While it doesn't exactly answer your question, I'll offer a slightly different approach:

($getdevice)  -split '\s+(?=Device #\d)' | select -Skip 1

Just for fun,

$drives = 
($getdevice)  -split '\s+(?=Device #\d)' | 
select -Skip 1 |
foreach { $Stringdata = 
          $_.replace(' : ','=') -replace 'Device #(\d)','Device = $1' -Replace 'Device is a (\w+)','DeviceIs = $1'
          New-Object PSObject -Property  $(ConvertFrom-StringData $Stringdata)
          } 

$drives | select Device,DeviceIs,'Total Size'

Device                             DeviceIs                           Total Size                        
------                             --------                           ----------                        
0                                  Hard drive                         70007 MB                          
1                                  Hard drive                         70007 MB                          
2                                  Hard drive                         286102 MB                         
3                                  Hard drive                         286102 MB                

Answer 4

try this variant:

[regex]::Matches($data,'(?im)device #\d((?!\s*Device #\d)\r?\n.)*?') | select value

Value
-----
Device #0
Device #1
Device #2
Device #3
Device #4