Replace or substring first set of numbers with regex

Question

I am struggling to find a way to get only the first set of numbers in a file name in PowerShell. The file names can be similar to the ones below but I only want to get the first string of numbers and nothing else.

Example file names:

123456 (12).csv
123456abc.csv
123456(Copy 1).csv
123456 (Copy 1).csv

What I am currently attempting:

$test = "123456 (12).csv" 
$POPieces = $test -match "^[0-9\s]+$" 
Write-Host $POPieces

What I'd expect from above:

What have you tried so far? Show some code for us to demonstrate an alternative/better fit solution or debug yours for you. — Will Webb
– Will Webb, Commented Oct 9, 2017 at 12:56
I have been overwriting most of what I tried with the next try so I don't remember most of it. I have tried about 20 different options and even found some that work perfect in the Regex test sites but in PowerShell do not. I have tried both .split and replace. This is the last try I did. $test = "123456 (12).csv" $POPieces = $test -match "^[0-9\s]+$" write-host $POPieces. so far I have been able to return all numbers but that includes numbers in parenthesis. — user1047982
– user1047982, Commented Oct 9, 2017 at 13:01
$ anchors it to the end, ^ anchors to the beginning, so you're telling powershell to match a regex that has one or more numbers or spaces, and nothing else. — Austin_Anderson
– Austin_Anderson, Commented Oct 9, 2017 at 13:23

Ansgar Wiechers · Accepted Answer · 2017-10-09 13:26:21Z

2

The -match operator stores the matches in the automatic variable $matches. However, your regular expression includes not only digits, but also whitespace (\s), so you won't necessarily get just the number. Change the expression to ^\d+ to match only a number at the beginning of the string. Use Get-ChildItem to enumerate the files, as Martin Brandl suggested.

$POPieces = Get-ChildItem 'C:\root\folder' -Filter '*.csv' |
            Where-Object { $_.Name -match '^\d+' } |
            ForEach-Object { $matches[0] }

answered Oct 9, 2017 at 13:26

Ansgar Wiechers

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