Use Variable in Replace

Question

I have a text file and want to regex/replace something with the content of a variable in PowerShell.

File: my.json
Variable in Powershell $version
Search for: version : "something"
Replace "something" with the content of the variable $version

Here is what I tried. Search and replace works as expected but the result is version : "$version".

(Get-Content my.json) -replace '(?<pre>"version"[\s]*:[\s]*)(?<V>"[^\"]*")', '$1"$version"' | Out-File my.json

Does this answer help at all? I think an escape sequence should alleviate your issue, either way. — gravity
– gravity, Commented Jul 26, 2016 at 14:13
Powershell has natively implements a JSON parser, you'd better use that if you can. Check out the ConvertFrom-JSON and ConvertTo-JSON methods — Aaron
– Aaron, Commented Jul 26, 2016 at 14:21

Ansgar Wiechers · Accepted Answer · 2016-07-26 14:13:23Z

4

To be able to use variables in the replacement string you need to use a double-quoted replacement string, meaning that you need to escape backreferences and nested double quotes:

(Get-Content my.json) -replace '...', "`$1`"$version`"" | ...

answered Jul 26, 2016 at 14:13

Ansgar Wiechers

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2 Comments

dknaack Over a year ago

Thanks for the answer and the edit! Have a great day!

Mathias R. Jessen Over a year ago

@dknaack if this answer solved your problem, please consider accepting it

Mathias R. Jessen · Accepted Answer · 2016-07-26 14:54:06Z

2

Ansgar's answer is perfectly valid, but ` escape sequences can be ugly and hinder readability.

I would personally use the -f format operator to concatenate the '$1' string literal and the value of $version:

(Get-Content my.json) -replace '...',('$1{0}' -f $version)

answered Jul 26, 2016 at 14:54

Mathias R. Jessen

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1 Comment

dknaack Over a year ago

Thanks! Looks better, yes

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