Find numbers after specific text in a string with RegEx

问题

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?

回答1:

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

回答2:

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
}

回答3:

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/'

来源：https://stackoverflow.com/questions/30639136/find-numbers-after-specific-text-in-a-string-with-regex