Can't access build variables from powershell script

Question

I'm trying to use the Build variables in a script. According to this documentation I should be able to use the following:

Write-Host "BUILD_DATE: $Env:BUILD_DATE"
Write-Host "BUILD_REV: $Env:BUILD_REV"

However, I only get the following output

BUILD_DATE:
BUILD_REV:

I've also tried this syntax:

Write-Host "BUILD_DATE: $(Env:BUILD_DATE)"
Write-Host "BUILD_REV: $(Env:BUILD_REV)"

Write-Host "BUILD_DATE: $(Build.Date)"
Write-Host "BUILD_REV: $(Build.Rev)"

But the first segment gives The term 'Env:BUILD_DATE' is not recognized and the second segment gives The term 'Build.Date' is not recognized

How can I use the build variables in my script?

Answer 1

^{Disclaimer: I know virtually nothing about Azure pipelines, so my answer is based on reading the docs. Do let us know if I got things wrong.}

Your first command uses the correct syntax for referencing environment variables in PowerShell (also inside an expandable (double-quoted) string).
(The other commands, based on subexpression operator $(...) , mistakenly try to execute commands named Env:BUILD_DAT , ... rather than referencing variables.)

Your problem seems to be that the targeted environment variables do not exist .

The list of predefined variables that are exposed as environment variables does not contain variables named Build.Date / $env:BUILD_DATE and Build.Rev / $env:BUILD_REV .

By contrast, variables named Date and Rev seemingly do exist - as you state, they are used in the default format definition for the Build.BuildNumber / $Env:BUILD_BUILDNUMBER build variable , $(Date:yyyyMMdd)$(Rev:.r) - but are seemingly of a different kind not exposed as env. vars. (unlike Build.BuildNumber / $Env:BUILD_BUILDNUMBER itself, which is exposed).

(I don't know where these variables are defined or how they are classified, and where this is documented - do tell us if you know.)

A quick workaround would be to split the value of $Env:BUILD_BUILDNUMBER into its constituent parts:

# Split the build number into date and revision, by "."
$date, $rev = $Env:BUILD_BUILDNUMBER -split '\.'

"BUILD_DATE: $date"
"BUILD_REV: $rev"