In my powershell script I am trying to get the python version in windows server 2008. This script just prints the version in console but I am not getting the value into variable.
Code:
$python = & python -V
write-host "Python Version: " + $python
Expected output:
Python Version: Python 2.7.8
Actual output:
Python 2.7.8
Python Version:
Any one help me out.
python.exe -V writes the version information to the Error output stream instead of the Success output stream. You get the observed output because the "error" message is printed before Write-Host is run, and the first command produces no output on the Success output stream to be assigned to $python, so the variable is empty when used in the Write-Host statement.
Change this line:
$python = & python -V
to this:
$python = & python -V 2>&1
and the problem will disappear.
Your code should work as designed. For whatever reason it is sending output to console instead of the variable. This code does work for me on PowerShell 3.0
$python = & python -V
write-host "Python Version: " + $python
You even mention in comments that similar commands work as expected like the following.
$python = & ping -n 1 localhost
write-host "Python Version: $python"
While I am not sure of the root cause you can write some code that will force capture of standard output into a System.Diagnostics.Process object. I took the code from another SO answer.
$pinfo = New-Object System.Diagnostics.ProcessStartInfo
$pinfo.FileName = "C:\Python34\python.exe"
$pinfo.Arguments = "-V"
$pinfo.RedirectStandardOutput = $true
$pinfo.UseShellExecute = $false
$p = New-Object System.Diagnostics.Process
$p.StartInfo = $pinfo
$p.Start() | Out-Null
$p.WaitForExit()
$stdout = $p.StandardOutput.ReadToEnd()
Write-Host "Python Version: $stdout"
I am not sure why a simple two liner does not work for you. What happens when you do something like this?. Again I dont have Python in my Path variable so i used the fullname of the file in my example.
Write-Host "Python Version: $(&"C:\Python34\python.exe" -V)"
or
Write-Host "Python Version: $(& python.exe -V)"
$python = & python -V 2>&1 this line solves my problem. Thanks @Matt for the response.
& ping -n 1 localhost. So I actually intalled Python to test just in case and your code does work. I had to dot source python.exe for testing but$python = &.\python.exe -Vbut the output worked fine. I'm also using PowerShell 3.0. What happens when you try$python = & ping -n 1 localhostandwrite-host "Python Version: $python".FYI variable will expand inside doublequotes.python.exe. The ping command inWrite-Hostdoes work. Interesting. Also use a backtick for code in comments.$puthon = & .\python.exe -V write-host "Python Version: $python"my output isPython 2.7.8 Python Version: