Replace a char in a text file using powershell

Question

I'm trying to replace a part on a text file. First i searched if it is present in the text file

$check = Get-Content sample.txt | Where-Object {$_.Contains('<add key="IIS_VERSION" value="7" />')}

if ($checkIISv)
{
Write-Host "IIS's version is already 7"
}
else
{
Write-Host "Update IIS version to 7"

# I want to place here a code that will replace the value="7" if it is not =7
# This value is usually not 7

}

Please help, I dont think the replace function can be used here since the "value" is considered as unknown.

Frode F. · Accepted Answer · 2016-05-13 23:22:34Z

2

You could use -replace with a regex-pattern to replace the value. However, this is an web/app xml-config so you should modify it as an XML-document. Ex.

#$xml = [xml](Get-Content "c:\folder\app.config")
$xml = [xml]@"
<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <appSettings>
    <add key="IIS_VERSION" value="8" />
    <add key="somekey" value="somevalue" />
  </appSettings>
</configuration>
"@

$IISVersion = $xml.SelectSingleNode("//add[@key='IIS_VERSION']")

if ($IISVersion.Value -eq 7)
{
    Write-Host "IIS's version is already 7"
}
else
{
    Write-Host "Update IIS version to 7"
    $IISVersion.Value = "7"
}

$xml.Save("c:\folder\app.config")

answered May 13, 2016 at 23:22

Frode F.

55.4k9 gold badges104 silver badges118 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Martin Brandl Over a year ago

thats probably the best solution.

Joey · Accepted Answer · 2016-05-13 23:22:35Z

1

If the line is always there you can of course use -replace. It does a regex replace, which can be used here:

$content = Get-Content sample.txt
if ($content -match '<add key="IIS_VERSION" value="7" />') {
  Write-Host "IIS's version is already 7"
} else {
  Write-Host "Update IIS version to 7"
  $content -replace '<add key="IIS_VERSION" value="[^"]+" />', '<add key="IIS_VERSION" value="7" />'
}

That's about the simplest way of doing that when using a string replace.

However, your file looks very much like XML. In which case it should actually be easier to use XML manipulation, which PowerShell offers as well:

$content = [xml](Get-Content sample.txt)
$iisKey = $content.SelectSingleNode("//add[@key = 'IIS_VERSION']")
if ($iisKey.value -eq 7) {
  Write-Host "IIS's version is already 7"
} else {
  Write-Host "Update IIS version to 7"
  $iisKey.value = '7'
  $content.Save((Resolve-Path sample.txt))
}

(Untested, and I don't do that often, but should be something alone those lines.)

answered May 13, 2016 at 23:22

Joey

357k88 gold badges704 silver badges699 bronze badges

4 Comments

Xander Vane Over a year ago

Thank you! I used your 1st script and just added " | Set-Content sample.txt" however I would like to understand this, what does this [^"] stands for? is it some kind of a wild card characters?

Xander Vane Over a year ago

I'm about to edit a couple of lines but it seems that the only one it edits is the last statement

Joey Over a year ago

[^"]+ is a regular expression that matches a string of character that are not a quotation marks. This is an easy way of specifying all text between two delimiters, in this case, everything between two quotation marks.

Xander Vane Over a year ago

thanks for this, anyway I have posted the updated script using your suggestion, however when I create another set to update another line the only one that changes is the last one, see my post. Thank you in advance

Community · Accepted Answer · 2017-05-23 11:51:33Z

0

The content looks like XML so you should consider using an xpath expression to select the node and change the value (See the answer from Frode F.). However, you can also do this with a regex (using a positive lookbehind to find the position)

$txt = Get-Content sample.txt
$regex = '(?<=<add key="IIS_VERSION" value=")[^"]+'
$txt -replace $regex, 7
$txt | Set-Content sample.txt

edited May 23, 2017 at 11:51

CommunityBot

11 silver badge

answered May 13, 2016 at 23:24

Martin Brandl

59.4k16 gold badges151 silver badges190 bronze badges

Comments

Xander Vane · Accepted Answer · 2016-05-16 19:09:08Z

0

My problem now is that it it only updates the bar code format and no longer the iis version if it is lower than 7

$path ='C:\Users\hello\Documents'

#Update the IIS version to 7

$content = Get-Content $path\Web.config

if ($content -match '<add key="IIS_VERSION" value="7" />') 
{
  Write-Host "IIS's version is already 7"
} 
else 
{
  Write-Host "Updated IIS version to 7"
  $content -replace '<add key="IIS_VERSION" value="[^"]+" />', '<add key="IIS_VERSION" value="7" />' | Set-Content $path\sample.txt
}


# Update the Barcode Format

if ($content -match '<add key="BARCODE_FORMAT" value="1" />')
{
    Write-Host "Barcode format is already 1"
}
else
{
    Write-Host "Updated Barcode Format to 1"
    $content -replace '<add key="BARCODE_FORMAT" value="[^"]+" />', '<add key="BARCODE_FORMAT" value="1" />' | Set-Content $path\sample.txt
}

answered May 16, 2016 at 19:09

Xander Vane

1972 gold badges5 silver badges20 bronze badges

1 Comment

Frode F. Over a year ago

We don't get a notification if you add a new answer. Use comments on the specific answer. Your problem happened because you include set-content inside your if-test, so it writes to the file twice (and the last overwrites the first with only barcode modified). If you changed to $content = $content -replace ... inside the tests (without any set-content) and use $content | set-content in the end of the script, it would work. Or use my approach which already does this. The barcode part was never a part of the question so you would need to expand my answer if you want to use it.

Collectives™ on Stack Overflow

Replace a char in a text file using powershell

4 Answers 4

1 Comment

4 Comments

Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

4 Comments

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related