Find numbers after specific text in a string with RegEx

Question

I have a multiline string like the following:

2012-15-08 07:04 Bla bla bla blup
2012-15-08 07:05 *** Error importing row no. 5: The import of this line failed because bla bla
2012-15-08 07:05 Another text that I don't want to search...
2012-15-08 07:06 Another text that I don't want to search...
2012-15-08 07:06 *** Error importing row no. 5: The import of this line failed because bla bla
2012-15-08 07:07 Import has finished bla bla

What I want is to extract all row numbers that have errors with the help of RegularExpression (with PowerShell). So I need to find the number between "*** Error importing row no. " and the following ":" as this will always give me the row number.

I looked at various other RegEx question but to be honest the answers are like chinese to me.

Tried to built RegEx with help of http://regexr.com/ but haven't been successful so far, for example with the following pattern:

"Error importing row no. "(.?)":"

Any hints?

Rubens Farias · Accepted Answer · 2015-06-04 09:03:32Z

35

Try this expression:

"Error importing row no\. (\d+):"

DEMO

Here you need to understand the quantifiers and escaped sequences:

. any character; as you want only numbers, use \d; if you meant the period character you must escape it with a backslash (\.)
? Zero or one character; this isn't what do you want, as you can here an error on line 10 and would take only the "1"
+ One or many; this will suffice for us
* Any character count; you must take care when using this with .* as it can consume your entire input

edited Jun 4, 2015 at 9:03

answered Jun 4, 2015 at 8:53

Rubens Farias

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Patric Over a year ago

Thanks for the additional information, helps me to understand RegEx better.

SomeShinyObject · Accepted Answer · 2015-06-04 08:59:38Z

3

Pretty straight forward. Right now your quoting is going to cause an error in the regex you wrote up. Try this instead:

$LogText = ""#Your logging stuff
[regex]$Regex = "Error importing row no\. ([0-9]*):"
$Matches = $Regex.Matches($LogText)
$Matches | ForEach-Object {
    $RowNum = $_.Groups[1].Value #(Waves hand) These are the rows you are looking for
}

answered Jun 4, 2015 at 8:59

SomeShinyObject

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Patric Over a year ago

Thank you also. Also working and many thanks for the PowerShell example, helped me clear things up.

Lalit Somnathe · Accepted Answer · 2016-09-07 18:40:32Z

0

THere could be multiple ways , few simple ones shown below might help:-

I took your log in a file called temp.txt.

cat temp.txt | grep " Error importing row no." | awk -F":" '{print $2}' | awk -F"." '{print $2}'

OR

cat temp.txt | grep " Error importing row no." | sed  's/\(.*\)no.\(.*\):\(.*\)/\2/'

answered Sep 7, 2016 at 18:40

Lalit Somnathe

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