PowerShell: combining paths using a variable

Question

This must be something obvious, but I can't get this to work.

I'm trying to build a variable that should contain the path to an existing file, using an environment variable ($env:programfiles(x86)). However I keep getting errors, and I fail to see why.

This works fine (if the file exists):

PS C:\> $f = "C:\Program Files (x86)" + '\sometextfile.txt'
PS C:\> $f
C:\Program Files (x86)\sometextfile.txt
PS C:\> gci $f
    Directory: C:\Program Files (x86)
Mode                LastWriteTime     Length Name
----                -------------     ------ ----
-a---        13/12/2010     14:03          0 sometextfile.txt
PS C:\>

However, this does not:

PS C:\> "$env:programfiles(x86)"
C:\Program Files(x86)
PS C:\> $f = "$env:ProgramFiles(x86)" + '\sometextfile.txt'
PS C:\> $f
C:\Program Files(x86)\sometextfile.txt
PS C:\> gci $f
Get-ChildItem : Cannot find path 'C:\Program Files(x86)\sometextfile.txt' because it does not exist.
At line:1 char:4
+ gci <<<<  $f
    + CategoryInfo          : ObjectNotFound: (C:\Program Files(x86)\sometextfile.txt:String) [Get-ChildItem], ItemNot
   FoundException
    + FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.Commands.GetChildItemCommand

What's happening, and how do I fix it?

Is the missing space in the second example just a typo? "Program Files (x86)" vs "Program Files(x86)" — craika
– craika, Commented Dec 13, 2010 at 13:52
no, on a 64bit system you get two env variables: ${env:programfiles} and ${env:programfiles(x86)} — jeroenh
– jeroenh, Commented Dec 13, 2010 at 15:53
Maybe useful: geekswithblogs.net/Lance/archive/2009/12/29/… — Kiquenet
– Kiquenet, Commented Apr 3, 2013 at 10:37

Peter Mortensen · Accepted Answer · 2018-10-18 19:38:43Z

26

Here is what is going on...

In any Windows PowerShell path empty characters or spaces need to be surrounded with a set of quotes or brackets. The PowerShell environment variable for the C:\Program Files (x86) is ${env:ProgramFiles(x86)}, not $env:ProgamFiles(x86) since PowerShell needs to escape the empty spaces in the real path.

If you use the '${env:ProgramFiles(x86)}' explicit environment variable, it works perfectly.

This won't work...

PS C:\> cd "$env:programfiles(x86)"
Set-Location : Cannot find path 'C:\Program Files(x86)' because it does not e
At line:1 char:3
+ cd <<<<  "$env:programfiles(x86)"
+ CategoryInfo          : ObjectNotFound: (C:\(x86):String)
+ FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.

or this...

PS C:\> $env:ProgramFiles(x86)
Unexpected token '(' in expression or statement.
At line:1 char:19
+ $env:ProgramFiles( <<<< x86)
+ CategoryInfo          : ParserError: ((:String) [], Parent
+ FullyQualifiedErrorId : UnexpectedToken

But this works great...

PS C:\> ${env:ProgramFiles(x86)}
C:\Program Files (x86)
PS C:\> $f = "${env:ProgramFiles(x86)}" + "\sometextfile.txt"
PS C:\> $f
C:\Program Files (x86)\sometextfile.txt
PS C:\> gci $f
Directory: C:\Program Files (x86)


Mode                LastWriteTime     Length Name
----                -------------     ------ ----
-a---        12/13/2010   8:58 AM          0 sometextfile.txt

edited Oct 18, 2018 at 19:38

Peter Mortensen

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answered Dec 13, 2010 at 14:09

thoughtpunch

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3 Comments

thoughtpunch Over a year ago

Per the previous poster, this is not a bug. In Powershell syntax, parentheses indicate a parameter that gets passed to a cmdlet or script. Since the environment variable stores a path has a set of parenthesis in it, the variable needs to be escaped and evaluated in-between the ${}. To see what I mean, try making a variable with parentheses in it, for example $dogs(areawesome) or $programs(x64) and you will get a 'Unexpected token '(' in expression or statement. The Powershell coders could have avoided this issue by making the environment variable "$env:ProgramFilesx86".

Keith Hill Over a year ago

Your answer is correct but the reason isn't. A space in the resultant path has nothing to do with why this particular envvar requires {}. If it did, then $env:ProgramFiles would also require {} but it doesn't. The reason ProgramFiles(x86) misbehaves is purely a parser issue. As the parser evaluates $env:ProgramFiles(x86), it sees a new 'Group' expression when it sees the opening parens which is not valid given the current context. You can see this with the PowerShell tokenizer e.g.: [management.automation.psparser]::Tokenize('$env:ProgramFiles(x86)', [ref]$errors).

JasonMArcher Over a year ago

The PowerShell developers didn't name that environment variable. :P

Peter Mortensen · Accepted Answer · 2018-08-24 19:47:49Z

2

That is weird and looks like a bug. Actually it is resolving the $env:programfiles variable and appending the rest of the string - which in this case just happens to be (x86).

This will work though:

$f =  ${env:ProgramFiles(x86)} + '\sometextfile.txt'

edited Aug 24, 2018 at 19:47

Peter Mortensen

31.4k22 gold badges110 silver badges134 bronze badges

answered Dec 13, 2010 at 14:09

craika

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