Extracting specific data from a string with regex and Powershell

Question

I want to extract from this string

blocked-process-report process id="process435d948" taskpriority="0" logused="0" waitresource="RID: 7:1:1132932:0" waittime= "3962166" ownerId="4641198" transactionname="SELECT" lasttranstarted="2011-09-13T17:21:54.950" XDES="0x80c5f060" lockMode="S" schedulerid="4" kpid="18444" status="susp ended" spid="58" sbid="0" ecid="0"

The value that is in bold, but only the value or 58. And this value can be with different values, sometimes 80 or 1000, etc. but always > 50.

How can I do this using regex and posh?

Jon Angliss · Accepted Answer · 2011-09-13 22:12:42Z

72

The quick and dirty:

$found = $string -match '.*spid="(\d+)".*'
if ($found) {
    $spid = $matches[1]
}

where $string is your above mentioned string. This would match any string that has spid="somenumberhere", and make the number into a matched group, which you can extract using $matches[1].

answered Sep 13, 2011 at 22:12

Jon Angliss

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4 Comments

Thymine Over a year ago

The .* will match anything before and after it on that line, its really only necessary if you used '^.*spid="(\d+)".*$'

Jon Angliss Over a year ago

You could leave them out, not sure on the performance impact of either way. It's probably a little cleaner/faster to leave them out, didn't really think much about it.

David Clarke Over a year ago

.* should typically not be used in regular expressions, the results can be unpredictable and performance slow because it will match the entire string before backtracking to find the next pattern in the regular expression. In this particular case only spid="(\d+)" is required for the match.

Mehrdad Mirreza Over a year ago

@JonAngliss: What would then be the not "quick and dirty" way?

General Grievance · Accepted Answer · 2024-12-03 16:13:17Z

3

Save your data in $string, then do

# Set $matches to null to avoid false positives from previous regex matches
$matches = $null
$string -match 'spid="(\d+)"'

If there is a match, the value you want will be in $matches[1]

edited Dec 3, 2024 at 16:13

General Grievance

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answered Sep 13, 2011 at 22:13

manojlds

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4 Comments

Kevin McCabe Over a year ago

Be careful, even if there is NOT a match you could still end up with data in $matches[1] from a PREVIOUS regex match.

Cheeso Over a year ago

And how does one avoid that pitfall? ^^

skelly Over a year ago

@Cheeso just set $matches = $null beforehand

General Grievance Dec 3, 2024 at 16:18

@Cheeso Use the other answer and just check it in an if statement. -match is intended as a comparison operator after all. You can even inline the variable.

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