Vista - New lines in regular expressions

Hello,

I am trying to search for a string pattern that includes new lines with the
select-string cmdlet. I was looking for something like \n to match a new line
in the regular expression but I can't seem to find anything.

Also, what would be the general syntax to include a new line in a string
(not speaking of regular expressions here) ?

Any help is appreciated.

Thanks,
Xavier

Hi

You can use the `n escape sequence:

$stringWithLineBreaks = "Power`nShell`nRocks!"
$stringWithLineBreaks

Power
Shell
Rocks!


-----
Shay Levi
$cript Fanatic
http://scriptolog.blogspot.com
Hebrew weblog: http://blogs.microsoft.co.il/blogs/scriptfanatic

# create a here-string with line breaks
PS:23 >$hs = @"
power
shell
rocks!
"@


PS:24 >$hs
power
shell
rocks

# test for line break , same as $hs -match "`n"
PS:25 >$hs -match "\n"
True

PS:26 >$hs -match "power\n"
True

# replace
PS:27 >$new = $hs -replace "power\n","power"
PS:28 >$new
powershell
rocks!

# same applies with `n
PS:29 >$new = $hs -replace "power`n","power"
PS:30 >$new
powershell
rocks!

# find string with line break
PS:39 >Select-String -InputObject $new -Pattern "powershell\n" -Quiet
True


# same with `n
PS:40 >Select-String -InputObject $new -Pattern "powershell`n" -Quiet
True


-----
Shay Levi
$cript Fanatic
http://scriptolog.blogspot.com
Hebrew weblog: http://blogs.microsoft.co.il/blogs/scriptfanatic

Thanks for the reply Shay,

I just tried `n and it does work in strings, but I still couldn't get the
select-string cmdlet to select a string pattern over multiple lines.
Actually, I don't know whether select-string is able to do that or not (it
might only apply the search pattern on each line) or if i'm using wrong
regular expressions.

Any idea on that ?

Thanks,
Xavier

"Shay Levi" wrote:

Xavier,

I know that matching text spanned accross multiple lines with line breaks
can be tricky (if possible)
not only in PowerShell, but this works (so I guess it's possible):

PS:23 >$hs = @"
power
shell
rocks!
"@

PS:24 >$new = $hs -replace "power`nshell","once again, powershell"
PS:25 >$new
once again, powershell
rocks!

Can you post a sample text with the regex pattern?

-----
Shay Levi
$cript Fanatic
http://scriptolog.blogspot.com
Hebrew weblog: http://blogs.microsoft.co.il/blogs/scriptfanatic

Thank you both for your input.

I find it very confusing that this doesn't work :

PS C:\Users\Xavier\Desktop> $somevar = "power`nshell`nrocks"
PS C:\Users\Xavier\Desktop> select-string -inputobject $somevar -pattern
"power`nshell" -quiet
True
PS C:\Users\Xavier\Desktop> set-content test.txt $somevar
PS C:\Users\Xavier\Desktop> get-content test.txt
power
shell
rocks
PS C:\Users\Xavier\Desktop> get-content test.txt | select-string "power"
-quiet
True
PS C:\Users\Xavier\Desktop> get-content test.txt | select-string
"power\nshell" -quiet
PS C:\Users\Xavier\Desktop> get-content test.txt | select-string
"power`nshell" -quiet
PS C:\Users\Xavier\Desktop>

So the pattern matches the variable content, but not the file content.
From what I understand, this is because the first variable is a string, and
the second is an array.
Keith's solution will work in that case :

PS C:\Users\Xavier\Desktop> $lines = get-content test.txt
PS C:\Users\Xavier\Desktop> $text = [string]::Join("`n", $lines)
PS C:\Users\Xavier\Desktop> select-string -inputobject $text -pattern
"power`nshell" -quiet
True

Thanks a lot,
Xavier


"Shay Levi" wrote:

You can check the "Windows PowerShell Cookbook" by Lee Holmes (O'reilly),
recipe #5.7:

"By default, regular expressions do not search across lines, but you can
use the singline (?s)
option to instruct them to do so."


PS > "Hello `n World" -match "Hello.*World"
False

PS > "Hello `n World" -match "(?s)Hello.*World"
True


Hope this helps

-----
Shay Levi
$cript Fanatic
http://scriptolog.blogspot.com
Hebrew weblog: http://blogs.microsoft.co.il/blogs/scriptfanatic

Thank you Shay, that's good to know.