I'm trying to use python in powershell

问题:

I'm trying to follow Zed Shaw's guide for Learning Python the Hard Way. I need to use python in Powershell. I have Python 2.7.3 installed in C:\Python27. Whenever I type python into Powershell, I get an error that says the term 'python' is not recognized as the name of a cmdlet, function, script file, or operable program. I also typed in this: [Environment]::SetEnvironmentVariable("Path", "$env:Path;C:\Python27", "User") That was a suggested solution provided, but typing python into Powershell still does nothing. I can type in "start python" and it opens up a window with python but I need it in Powershell. Thanks.

回答1:

Try setting the path this way:

 $env:path="$env:Path;C:\Python27"

回答2:

For what's worth, this command did it for me (Python3.3) :

[System.Environment]::SetEnvironmentVariable("PATH", $Env:Path + ";C:\Python33", "Machine")

I just had to restart the Powershell after that.

回答3:

$env:path="$env:Path;C:\Python27" will only set it for the current session. Next time you open Powershell, you will have to do the same thing again.

The [Environment]::SetEnvironmentVariable() is the right way, and it would have set your PATH environment variable permanently. You just have to start Powershell again to see the effect in this case.

回答4:

For a permanent solution I found the following worked:

[Environment]::SetEnvironmentVariable("Path", "$env:Path;C:\Python 3.5")

回答5:

This works for me permanently:

[Environment]::SetEnvironmentVariable("Path", "$env:Path;C:\Python27","User")

回答6:

The Directory is not set correctly so Please follow these steps.

1. "MyComputer">Right Click>Properties>"System Properties">"Advanced" tab
2. "Environment Variables">"Path">"Edit"

3. In the "Variable value" box, Make sure you see following:

   ;c:\python27\;c:\python27\scripts

4. Click "OK", Test this change by restarting your windows powershell. Type

   python

5. Now python version 2 runs! yay!

回答7:

Sometimes you install Python on Windows and it doesn't configure the path correctly.

Make sure you enter [Environment]::SetEnvironmentVariable("Path", "$env:Path;C:\Python27", "User")
in PowerShell to configure it correctly.

You also have to either restart PowerShell or your whole computer to get it to really be fixed.

回答8:

From the Python Guide, this is what worked for me (Python 2.7.9): [Environment]::SetEnvironmentVariable("Path", "$env:Path;C:\Python27\;C:\Python27\Scripts\", "User")

回答9:

Try the Command this way:

PS C:\Users\XXX>python.exe

instead of:

C:\Users\XXX>python

回答10:

Just eliminate the word "User". It will work.

回答11:

As MaxPRafferty mentioned:

Just a note to anyone landing here from google, the answers setting path are all correct, but this problem probably stems from not giving the python installer administrative rights it needs to set the path itself. An alternative may be to simply right click the installer and select run as administrator, then repair the installation. If that still doesn't work, choose the [Environment] answer below that corresponds to your python version and installation directory. – MaxPRafferty Nov 18 '15 at 20:06

Maybe it is wise to let Python installer to add the path itself. The trap here is that by default Python installer does NOT add path for you. You should look carefully (by scrolling down to see what has been installed) during the installation process instead of directly nexting to the end.

What he missed saying is that you cannot run as administrator once you have installed it. Uninstall and reinstall may do, but the simplest is to right click and Troubleshoot compatibility, being careful this time to check the 'add path' in the "what to install" dialog before hiting next. Then restart powershell. Voilà. It works for me.

回答12:

To be able to use Python immediately without restarting the shell window you need to change the path for the machine, the process and the user.

Function Get-EnvVariableNameList {
    [cmdletbinding()]
    $allEnvVars = Get-ChildItem Env:
    $allEnvNamesArray = $allEnvVars.Name
    $pathEnvNamesList = New-Object System.Collections.ArrayList
    $pathEnvNamesList.AddRange($allEnvNamesArray)
    return ,$pathEnvNamesList
}

Function Add-EnvVarIfNotPresent {
Param (
[string]$variableNameToAdd,
[string]$variableValueToAdd
   ) 
    $nameList = Get-EnvVariableNameList
    $alreadyPresentCount = ($nameList | Where{$_ -like $variableNameToAdd}).Count
    #$message = ''
    if ($alreadyPresentCount -eq 0)
    {
    [System.Environment]::SetEnvironmentVariable($variableNameToAdd, $variableValueToAdd, [System.EnvironmentVariableTarget]::Machine)
    [System.Environment]::SetEnvironmentVariable($variableNameToAdd, $variableValueToAdd, [System.EnvironmentVariableTarget]::Process)
    [System.Environment]::SetEnvironmentVariable($variableNameToAdd, $variableValueToAdd, [System.EnvironmentVariableTarget]::User)
        $message = "Enviromental variable added to machine, process and user to include $variableNameToAdd"
    }
    else
    {
        $message = 'Environmental variable already exists. Consider using a different function to modify it'
    }
    Write-Information $message
}


Function Get-EnvExtensionList {
    $pathExtArray =  ($env:PATHEXT).Split("{;}")
    $pathExtList = New-Object System.Collections.ArrayList
    $pathExtList.AddRange($pathExtArray)
    return ,$pathExtList
}


Function Add-EnvExtension {
Param (
[string]$pathExtToAdd
   ) 
    $pathList = Get-EnvExtensionList
    $alreadyPresentCount = ($pathList | Where{$_ -like $pathToAdd}).Count
    if ($alreadyPresentCount -eq 0)
    {
        $pathList.Add($pathExtToAdd)
        $returnPath = $pathList -join ";"
        [System.Environment]::SetEnvironmentVariable('pathext', $returnPath, [System.EnvironmentVariableTarget]::Machine)
        [System.Environment]::SetEnvironmentVariable('pathext', $returnPath, [System.EnvironmentVariableTarget]::Process)
        [System.Environment]::SetEnvironmentVariable('pathext', $returnPath, [System.EnvironmentVariableTarget]::User)
        $message = "Path extension added to machine, process and user paths to include $pathExtToAdd"
    }
    else
    {
        $message = 'Path extension already exists'
    }
    Write-Information $message
}

Function Get-EnvPathList {
    [cmdletbinding()]
    $pathArray =  ($env:PATH).Split("{;}")
    $pathList = New-Object System.Collections.ArrayList
    $pathList.AddRange($pathArray)
    return ,$pathList
}

Function Add-EnvPath {
Param (
[string]$pathToAdd
   ) 
    $pathList = Get-EnvPathList
    $alreadyPresentCount = ($pathList | Where{$_ -like $pathToAdd}).Count
    if ($alreadyPresentCount -eq 0)
    {
        $pathList.Add($pathToAdd)
        $returnPath = $pathList -join ";"
        [System.Environment]::SetEnvironmentVariable('path', $returnPath, [System.EnvironmentVariableTarget]::Machine)
        [System.Environment]::SetEnvironmentVariable('path', $returnPath, [System.EnvironmentVariableTarget]::Process)
        [System.Environment]::SetEnvironmentVariable('path', $returnPath, [System.EnvironmentVariableTarget]::User)
        $message = "Path added to machine, process and user paths to include $pathToAdd"
    }
    else
    {
        $message = 'Path already exists'
    }
    Write-Information $message
}

Add-EnvExtension '.PY'
Add-EnvExtension '.PYW'
Add-EnvPath 'C:\Python27\'