Replace regex token environment variable in PowerShell
A bit of a PowerShell duel. I am trying to replace tokens in a text file with environment variable values. For example, suppose my input file looks like this:
Hello [ENV(USERNAME)], your computer name is [ENV(COMPUTERNAME)]
and runs [ENV(OS)]
I've tried the following:
Get-Content test.txt | ForEach {$_ -replace '\[ENV\((\w+)\)\]', "$env:$1" }
This gives an error:
At line:1 char:74
+ Get-Content test.txt | ForEach {$_ -replace '\[ENV\((\w+)\)\]', "$env:$1 ...
+ ~~~~~
Variable reference is not valid. ':' was not followed by a valid variable name character. Consider using ${} to delimit the name.
+ CategoryInfo : ParserError: (:) [], ParentContainsErrorRecordException
+ FullyQualifiedErrorId : InvalidVariableReferenceWithDrive
I've also tried:
Get-Content test.txt | ForEach {$_ -replace '\[ENV\((\w+)\)\]', [environment]::GetEnvironmentVariable($1) }
But that doesn't get the variables and gives me this as output:
Hello , your computer is named
and runs
I tried to call a function that I defined myself, but I get another error:
At D:\tfs\HIPv3\prod\Dev\Tools\EnvironmentResolve.ps1:13 char:72
+ Get-Content test.txt | ForEach {$_ -replace '\[ENV\((\w+)\)\]', GetEnvVa ...
+ ~~~~~~~~
Missing expression after ','.
At D:\tfs\HIPv3\prod\Dev\Tools\EnvironmentResolve.ps1:13 char:73
+ Get-Content test.txt | ForEach {$_ -replace '\[ENV\((\w+)\)\]', GetEnvVa ...
+ ~~~~~~~~
Unexpected token 'GetEnvVar' in expression or statement.
+ CategoryInfo : ParserError: (:) [], ParseException
+ FullyQualifiedErrorId : MissingExpressionAfterToken
Does anyone know how to make this work?
I got it:
$string = 'Hello [ENV(USERNAME)], your computer name is [ENV(COMPUTERNAME)] and runs [ENV(OS)]'
$regex = '\[ENV\(([^)]+)\)]'
[regex]::Matches($string,$regex) |
foreach {
$org = $_.groups[0].value
$repl = iex ('$env:' + $_.groups[1].value)
$string = $string.replace($org,$repl)
}
$string
"$env:$1"
Use '$env:$1'
(single quotes) instead of (double quotes) and you should be fine. PowerShell will expand variables in a double quoted string. $1
Not a PowerShell variable in your context : it's a regex token.
Instead, [ENV(...)]
why not use %...%
?
$string = 'Hello %USERNAME%, your computer name is %COMPUTERNAME% and runs %OS%'
[System.Environment]::ExpandEnvironmentVariables($string)
Which gives me: Hi IanG, your computer name is 1EUKCOL1184 and starts Windows_NT