PowerShell Regular Expression Multiline

Question

I want to match following multiline in a text file.

[1750256247]
;Rev: B,5

I tried following, however could not succeed. Could you please help me?

$fileContent | Select-String "(?smi)(^[1750256247](-|\s*$))(^;Rev: B,5$)" -AllMatches | Foreach {$.Matches} | Foreach {$.Value}

You can also use `$fileContent | Select-String "(?i)\[1750256247][-\s]*;Rev: B,5" -AllMatches | Foreach {$_.Matches} | Foreach {$_.Value}` — Wiktor Stribiżew, Jan 15 '16 at 08:10
npinti's does not work on my end either. Did you try `$fileContent | Select-String "(?i)\[1750256247][-\s]*;Rev: B,5" -AllMatches | Foreach {$_.Matches} | Foreach {$_.Value}`? BTW, do you mean a `\r\n` linebreak or a `
`? — Wiktor Stribiżew, Jan 15 '16 at 08:56
Hi stribizhev, Yes I tried yours also. The same happened. I can not understand why. I mean [CR][LF] — AydinK, Jan 15 '16 at 09:00
String is as follows : [1750256247][CR][LF];Rev: B,5[CR][LF] — AydinK, Jan 15 '16 at 09:12
I found a solution. Please check this post. http://stackoverflow.com/questions/21911293/multiline-regex-in-powershell — AydinK, Jan 17 '16 at 14:24

npinti · Answer 1 · 2016-01-15T08:19:47.120

0

Not exactly 100% sure what you are after, but changing your expression to this: (?smi)(^\[1750256247\](.|-|\s*$))(^;Rev: B,5$) (example here) works.

Some issues with your expression:

In regex syntax, the [ and ] characters denote character sets, that is, a set of characters of which the engine will attempt to match one of. If you need to match the actual [ and ] characters, you will need to escape them through the use of the \ character.
You are using the s modifier, thus allowing the period character to also match newlines, but you are not using the period character.

EDIT: As per @stribizhev's suggestion, you can use (?smi)(^\[1750256247](.|-|\s*$))(^;Rev: B,5$). Personally I would go for the first option because I consider it more readable, but opinions will most likely differ on this.

edited Jan 15 '16 at 08:19

answered Jan 15 '16 at 08:02

npinti

51,780
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Only `[` should be escaped here. `[` must be escaped outside of character class, and `]` should be escaped inside a character class if not in the initial position. – Wiktor Stribiżew Jan 15 '16 at 08:05
@stribizhev: So `\[foo]` will match `[foo]`? – npinti Jan 15 '16 at 08:08
Yes, the `]` is disambiguated as a literal symbol in most regex flavors. In Powershell, .NET regex is used, so, it will work like this. – Wiktor Stribiżew Jan 15 '16 at 08:09
Hi npinti,Thank you for the quick reply. There is a line break after "[1750256247]". Then comes ";Rev: B,5" at the beginning of nest line. I tried what you wrote but did not work. – AydinK Jan 15 '16 at 08:09
@stribizhev: I see what you mean. Don't you think it hinders readability? – npinti Jan 15 '16 at 08:11
@npinti: I think the opposite – Wiktor Stribiżew Jan 15 '16 at 08:11
@stribizhev: I see. I've added your response as well for completeness. – npinti Jan 15 '16 at 08:20

score 0 · Answer 2 · answered Jan 15 '16 at 13:18

I find multiline regex easier to write and more intuitive to read if you build the regex in a here-string, with the newlines embedded.

$regex = @'
(?ms)\[1750256247\]\s*
;Rev: B,5\s*
'@

Just paste the literal string you're trying to match into the regex and then escape and add metacharacters for things like trailing whitespace as needed.

PowerShell Regular Expression Multiline

2 Answers2