How to access file paths in PowerShell containing special characters

13
votes

I am calling PowerShell from within a Java application (through the Windows command prompt) to read various file attributes.

For example,

powershell (Get-Item 'C:\Users\erlpm\Desktop\Temp\s p a c e s.txt').creationTime

I am enclosing the file path in single quotes, because it may contain spaces. It worked fine, until I encountered a file path containing square brackets, which seem to be interpreted as a wildcard character. I managed to solve it by adding the -literalPath parameter:

powershell (Get-Item -literalpath 'C:\Users\erlpm\Desktop\Temp\brackets[].txt').creationTime

So far, so good... But file paths may also contain single quotes, dollar signs, ampersands, etc., and all these characters seem to have a specific function in PowerShell for which the -literalPath parameter does not seem to work.

I tried enclosing the path with double quotes or escaping with the `character, but that did not solve my problem either :-(

Any suggestions on how to pass a file path to PowerShell which may contain spaces, single quotes, square brackets, ampersands, dollar signs, etc.?

Someone here already showed me how to get it working from within PowerShell, but somehow the answer has been removed(?).

Anyway, I did create a file called $ & ' [].txt. This works form within PowerShell (needed to escape the &):

Get-Item -LiteralPath "C:\Users\erlpm\Desktop\Temp\`$ & ' [].txt"


    Directory: C:\Users\erlpm\Desktop\Temp


Mode                LastWriteTime     Length Name
----                -------------     ------ ----
-a---        2012-08-23     14:22          0 $ & ' [].txt

But when I execute the same PowerShell command through the Windows command prompt, ...

powershell Get-Item -LiteralPath "C:\Users\erlpm\Desktop\Temp\`$ & ' [].txt"

... I get this error:

Ampersand not allowed. The & operator is reserved for future use; use "&" to pass ampersand as a string.
At line:1 char:55 \

  • Get-Item -LiteralPath C:\Users\erlpm\Desktop\Temp`$ & <<<< ' [].txt \
    • CategoryInfo : ParserError: (:) [], ParentContainsErrorRecordException \
    • FullyQualifiedErrorId : AmpersandNotAllowed

Using the -command parameter and putting the PowerShell command between {} gives exactly the same error message ...

powershell -command {Get-Item -LiteralPath "C:\Users\erlpm\Desktop\Temp\`$ & ' [].txt"}
3
powershell
Could you provide a few examples of paths which are not working, and the exact error you get? You have only provided working paths so far, so it's hard to tell where the problem is. – latkin
I updated my question and added some working and non-working examples. As you can see, I can get it to work from within the Powershell prompt, but not by executng powershell from the Windows command prompt. – jeroen_de_schutter
I reproduced your issue by creating a file named "$ * ' [].txt". Then, from a powershell prompt, I typed get-item <tab> and powershell completed the filename for me, but I can't paste the completed filename in here because markdown eats all the special characters. Give it a try and see if that helps. – joXn
For reference, here are the PowerShell wildcard docs: docs.microsoft.com/en-us/powershell/module/… – Ohad Schneider

3 Answers

10
votes

This is really a question about cmd.exe string escaping, then. Combining cmd and PowerShell string escaping is a total nightmare. After quite a few attempts, I got your specific example to work:

powershell.exe -nologo -noprofile -command ^&{ dir -LiteralPath ^"""".\`$ & ' [].txt"" }

    Directory: C:\Users\latkin
Mode                LastWriteTime     Length Name
----                -------------     ------ ----
-a---         8/23/2012   8:46 AM          0 $ & ' [].txt

Totally intuitive, right?

You can spend 15 minutes wrestling with escape sequences every time, or you can try some other approaches.

Put the file name in a text file, and read it out of there.

powershell.exe -command "&{dir -literal (gc .\filename.txt)  }"

or

Use a script

powershell.exe -file .\ProcessFiles.ps1  # In processfiles.ps1 you are in fully powershell environment, so escaping is easier

or

Use -EncodedCommand

See powershell.exe -? (last item shown) or http://dmitrysotnikov.wordpress.com/2011/07/06/passing-parameters-to-encodedcommand/

6
votes

This thread is 5 years old so maybe times have changed, but the current answer that worked for me was to use the backtick (`) symbol to escape the special character.

In my case, it was a dollar sign in a directory path that was failing. By putting a backtick before the dollar sign, everything worked.

Before:

$dir = "C:\folder$name\dir"  # failed

After:

$dir = "C:\folder`$name\dir" # succeeded
6
votes

If you can write the path to a temporary .txt file, the following works OK:

(Get-Item -literalpath (gc 'C:\Temp\path.txt')).creationTime

The file @ C:\Temp\path.txt contains the path with special characters in it, other than this I think you would have to escape each special character on a per path basis.

In addition to the hack above, it appears PowerShell V3 may help out here with the addition of a new 'magic parameter' language feature. Specifically, see the section headed 'Easier Reuse of Command Lines From Cmd.exe' here and because I hate link-rot, here it is, shamelessly reproduced below:

Easier Reuse of Command Lines From Cmd.exe

The web is full of command lines written for Cmd.exe. These commands lines work often enough in PowerShell, but when they include certain characters, e.g. a semicolon (;) a dollar sign ($), or curly braces, you have to make some changes, probably adding some quotes. This seemed to be the source of many minor headaches.

To help address this scenario, we added a new way to “escape” the parsing of command lines. If you use a magic parameter --%, we stop our normal parsing of your command line and switch to something much simpler. We don’t match quotes. We don’t stop at semicolon. We don’t expand PowerShell variables. We do expand environment variables if you use Cmd.exe syntax (e.g. %TEMP%). Other than that, the arguments up to the end of the line (or pipe, if you are piping) are passed as is. Here is an example:

 echoargs.exe --% %USERNAME%,this=$something{weird}
 Arg 0 is <jason,this=$something{weird}>