CODEWITHSUNDEEP
regexpowershellreplace
Rad
Rad

Reputation: 963

Powershell capture group - insert some text after the matching line

I am trying to insert a line with powershell statement into multiple script files.

The content of the files are like these (3 cases)

"param($installPath)"

- no CRLF characters, only 1st line

"param($installPath)`r`n`"

- with CRLF characters, no 2nd line

"param($installPath)`r`n`some text on the second line"

- with CRLF characters, non-empty 2nd line

I want to insert some text (poweshell statement in the second line 'r'n$myvar = somethingelse) so it is immediately below the first line appending 'r'n characters to the first line if they don't exist

"param($installPath)`r`nmyvar = somethingelse"

- ADD CRLF character first to the 1st line and ADD $myvar = somethingelse on the 2nd line

"param($installPath)`r`n`$myvar = somethingelse"

- ONLY ADD "$myvar = somethingelse" on the 2nd line, since CRLF already exists (no need to add the ending rn)

"param($installPath)`r`n`$myvar = somethingelse`r`n`some text on the second line"**

- ADD "$myvar = somethingelse'r'n" on the 2nd line (CRLF already exists on the first line) and APPEND CRLF to it so the existing text on the second line will move to 3rd line.

I was trying to use this regular expression: "^param(.+)(?:(rn))" and this replacement, but with no success ($1 is the first capture group, $2 is non capture group which I ignore even if something is found and I explicitly add CRLF after $1 capture group) "$1rnmyvar = somethingelse"

Thanks,

Rad

Upvotes: 0

Views: 1730

Answers (1)

MikeM
MikeM

Reputation: 13641

The following use of -replace seems to match your requirements

$content = "param(some/path)"
#$content = "param(some/path)`r`n"  
#$content = "param(some/path)`r`n`some text on the second line"

$content = $content -replace "^(param\(.+\))(?:\r\n$)?",
        ( '$1' + "`r`nmyvar = somethingelse" )

Write-Host "`n$content"

Note that references to capture groups have to be in single quotes.

The optional, uncaptured (?:\r\n$) group ensures that CRLF is removed if there is nothing, i.e. the end of string $, following it.

Edit

If what follows param is not known, the following regex could be used instead.
It uses [^\r\n] to capture characters that are not newlines.

"^(param[^\r\n]*)(?:\r\n$)?"

Upvotes: 1

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