Powershell script is failing when files with a single quote are passed through script. Alternate batch file is also failing with & and ! characters

Question

This is a deceptively complex issue, but I'll do my best to explain the problem.

I have a simple wrapper script as follows called VSYSCopyPathToClipboard.ps1:

param (
    [Parameter(Mandatory,Position = 0)]
    [String[]]
    $Path,

    [Parameter(Mandatory=$false)]
    [Switch]
    $FilenamesOnly,

    [Parameter(Mandatory=$false)]
    [Switch]
    $Quotes
)

if($FilenamesOnly){
    Copy-PathToClipboard -Path $Path -FilenamesOnly
}else{
    Copy-PathToClipboard -Path $Path
}

Copy-PathToClipboard is just a function I have available that copies paths/filenames to the clipboard. It's irrelevant to the issue, just assume it does what it says.

The way the wrapper is called is through the Windows right click context menu. This involves creating a key here: HKEY_CLASSES_ROOT\AllFilesystemObjects\shell\.

Mine looks like this:

The command is as follows:

"C:\Tools\scripts\BIN\SingleInstanceAccumulator.exe" -q:' "-c:pwsh -noprofile -windowstyle hidden -Command "C:\Tools\scripts\VSYSCopyPathToClipboard.ps1" -Path $files" "%1"

And similarly for the "Copy as Filename":

"C:\Tools\scripts\BIN\SingleInstanceAccumulator.exe" -q:' "-c:pwsh -noprofile -windowstyle hidden -Command "C:\Tools\scripts\VSYSCopyPathToClipboard.ps1" -FilenamesOnly -Path $files" "%1"

I am using a tool here called SingleInstanceAccumulator. This allows me to pass multiple selected files to a single instance of PowerShell. If I didn't use this program and ran my command with multiple files selected it would launch multiple instances of PowerShell for each file selected. It's the next best thing to creating your own shell extension and implementing IPC etc.

This has been working great until today when I encountered a file with a single quote in its filename (I.E.testing'video.mov) and the entire script failed. It's failing because the delimiter I'm using with SingleInstanceAccumulator is also a single quote and PowerShell sees no matching quote... thus errors out.

I could fix this if my variables were static by just doubling up the offending single quote, but since my parameters are files I have no opportunity to escape the single quote beyond renaming the file itself ... which is a non-solution.

So now I have no clue how to handle this.

My first try at solving the problem was as such:

---

1. Create a batch file and redirect my registry command to it.
2. Change the SingleInstanceAccumulator delimiter to '/' (All files will be separated by a forward slash.)
3. Replace the offending single quote to two single quotes.
4. Replace the '/' delimiters with single quotes.
5. Finally pass the whole argument list back to Powershell.

This image demonstrates how the above process looks:

This is the batch file's code:

@echo off
setlocal EnableDelayedExpansion

:: This script is needed to escape filenames that have 
:: a single quote ('). It's replaced with double single
:: quotes so the filenames don't choke powershell
:: echo %cmdcmdline%

set "fullpath=%*"

echo Before 
echo !fullpath!
echo ""

echo After
set fullpath=%fullpath:'=''%
set fullpath=%fullpath:/='%
echo !fullpath!

:: pwsh.exe -noprofile -windowstyle hidden -command "%~dpn0.ps1 -Path !fullpath!

pause

Once I got that wired up I started celebrating ... until I hit a file with an ampersand (&) or an exclamation point (!). Everything fell apart again. I did a whole bunch of google-fu with regards to escaping the & and ! characters but nothing suggested worked at all for me.

If I pass 'C:\Users\futur\Desktop\Testing\Video Files\MOV Batch\testing&video.mov' into my batch file, I get 'C:\Users\futur\Desktop\Testing\Video Files\MOV Batch\testing back.

It truncates the string at the exact position of the ampersand.

I feel like there has to be a way to solve this, and that I'm missing something stupid. If I echo %cmdcmdline% it shows the full commandline with the &, so it's available somehow with that variable.

In conclusion: I'm sorry for the novel of a post. There is a lot of nuance in what I'm trying to accomplish that needs to be explained. My questions are as follows:

1. Can I accomplish this with Powershell only and somehow pre-escape single quotes?
2. Can I accomplish this with a batch file, and somehow pre-escape & and ! (and any other special characters that would cause failure)?

Any help at all would be hugely appreciated.

Edit1:

---

So in the most hideous and hackish way possible, I managed to solve my problem. But since it's so horrible and I feel horrible for doing it I am still looking for a proper solution.

Basically, to recap, when I do either of these variable assignments:

set "args=%*"
set "args=!%*!"
echo !args!

& and ! characters still break things, and I don't get a full enumeration of my files. Files with & get truncated, etc.

But I noticed when I do:

set "args=!cmdcmdline!"
echo !args!

I get the full commandline call with all special characters retained:

C:\WINDOWS\system32\cmd.exe /c ""C:\Tools\scripts\VSYSCopyPathToClipboardTest.bat" /C:\Users\futur\Desktop\Testing\Video Files\MOV Batch\KylieCan't.mov/,/C:\Users\futur\Desktop\Testing\Video Files\MOV Batch\The !Rodinians - Future Forest !Fantasy - FFF Trailer.mov/,/C:\Users\futur\Desktop\Testing\Video Files\MOV Batch\Yelle - Je Veu&x Te Voir.mov/,/C:\Users\futur\Desktop\Testing\Video Files\MOV Batch\Erik&Truffaz.mov/,/C:\Users\futur\Desktop\Testing\Video Files\MOV Batch\my_file'name.mov/,/C:\Users\futur\Desktop\Testing\Video Files\MOV Batch\testing&video.mov/"

So what I did was simply strip out the initial C:\WINDOWS\system32\cmd.exe /c ""C:\Tools\scripts\VSYSCopyPathToClipboardTest.bat" part of the string:

@echo off
setlocal enableDelayedExpansion

set "args=!cmdcmdline!"
set args=!args:C:\WINDOWS\system32\cmd.exe=!
set args=!args: /c ""C:\Tools\scripts\VSYSCopyPathToClipboard.bat" =!
set args=!args:'=''!
set args=!args:/='!
set args=!args:~0,-1!

echo !args!

pwsh.exe -noprofile -noexit -command "%~dpn0.ps1 -Path !args!

And... it works flawlessly. It handles any crazy character I throw at it without needing to escape anything. I know It's totally the most degenerate garbage way of approaching this, but not finding a solution anywhere leads me to desperate measures. :)

I am probably going to make the string removal a bit more universal since it literally breaks if I change the filename.

I am still VERY much open to other solutions should anyone know of a way to accomplish the same thing in a more elegant way.

Answer 1

• A fully robust solution based on PowerShell's -Command (-c) CLI parameter that can handle ' characters in paths as well as $ and ` ones requires a fairly elaborate workaround, unfortunately:^[1]

  • Use an aux. cmd.exe call that echoes the $files macro as-is and pipe that to pwsh.exe; make SingleInstanceAccumulator.exe double-quote the individual paths (as it does by default), but use no delimiter (d:"") in order to effectively output a string in the form "<path 1>""<path 2>""...

  • Make pwsh.exe reference the piped input via the automatic $input variable and split it into an array of individual paths by " (removing empty elements that are a side effect of splitting with -ne ''). The necessity for providing the paths via the pipeline (stdin) is discussed in more detail in this related answer.

  • The resulting array can safely be passed to your scripts.

• Also, enclose the entire -Command (-c) argument passed to pwsh.exe in \"...\" inside the "-c:..." argument.

  • Note: You may get away without doing this; however, this would result in whitespace normalization, which (however unlikely) would alter a file named, say, foo bar.txt to foo bar.txt (the run of multiple spaces was normalized to a single space).

  • Escaping " characters as \" is necessary for PowerShell's -Command (-c) CLI parameter to treat them verbatim, as part of the PowerShell code to execute that is seen after initial command-line parsing, during which any unescaped " characters are stripped.

Therefore, the first command stored in the registry should be (adapt the second one analogously; note that there must be no space between the echo $files and the subsequent |):

"C:\Tools\scripts\BIN\SingleInstanceAccumulator.exe" -d:"" "-c:cmd /c echo $files| pwsh.exe -noprofile -c \"& 'C:\Tools\scripts\VSYSCopyPathToClipboard.ps1' -Path ($input -split '\\\"' -ne '')\"" "%1"

Note:

If you modified your scripts to accept the paths as individual arguments rather than as an array, a much simpler solution via the -File CLI parameter (rather than -Command (-c)) is possible. This could be as simple as decorating the $Path parameter declaration with [Parameter(ValueFromRemainingArguments)] and then invoking the script without naming the target parameter explicitly (-Path):

"C:\Tools\scripts\BIN\SingleInstanceAccumulator.exe" -d:" " "-c:pwsh.exe -noprofile -File \"C:\Tools\scripts\VSYSCopyPathToClipboard.ps1\" $files" "%1"

Note the use of -d:" " to make SingleInstanceAccumulator.exe space-separate the (double-quoted by default) paths. Since -File passes the pass-through arguments verbatim, there is no concern about what characters the paths are composed of.

---

Self-contained PowerShell sample code:

The following code defines a Copy Paths to Clipboard shortcut-menu command for all file-system objects (except drives):

• No separate .ps1 script is involved; instead, the code passed to -Command / -c directly performs the desired operation (copying the paths passed to the clipboard).

• The following helps with troubleshooting:

  • The full command line with which PowerShell was invoked ([Environment]::CommandLine) is printed, as is the list of paths passed ($file)

  • -windowstyle hidden is omitted to keep the console window in which the PowerShell commands visible and -noexit is added so as to keep the window open after the command has finished executing.

Prerequisites:

• Download and build the SingleInstanceAccumulator project using Visual Studio (using the .NET SDK is possible, but requires extra work).

• Place the resulting SingleInstanceAccumulator.exe file in one of the directories listed in your $env:Path environment variable. Alternatively, specify the full path to the executable below.

Note:

• reg.exe uses \ as its escape character, which means that \ characters that should become part of the string stored in the registry must be escaped, as \\.

• The sad reality as of PowerShell 7.2 is that an extra, manual layer of \-escaping of embedded " characters is required in arguments passed to external programs. This may get fixed in a future version, which may require opt-in. See this answer for details. The code below does this by way of a -replace '"', '\"' operation, which can easily be removed if it should no longer be necessary in a future PowerShell version.

# RUN WITH ELEVATION (AS ADMIN).

# Determine the full path of SingleInstanceAccumulator.exe:
# Note: If it isn't in $env:PATH, specify its full path instead.
$singleInstanceAccumulatorExe = (Get-Command -ErrorAction Stop SingleInstanceAccumulator.exe).Path

# The name of the shortcut-menu command to create for all file-system objects.
$menuCommandName = 'Copy Paths To Clipboard'

# Create the menu command registry key.
$null = reg.exe add "HKEY_CLASSES_ROOT\AllFilesystemObjects\shell\$menuCommandName" /f /v "MultiSelectModel" /d "Player"
if ($LASTEXITCODE) { throw }

# Define the command line for it.
# To use *Windows PowerShell* instead, replace "pwsh.exe" with "powershell.exe"
# SEE NOTES ABOVE.
$null = reg.exe add "HKEY_CLASSES_ROOT\AllFilesystemObjects\shell\$menuCommandName\command" /f /ve /t REG_EXPAND_SZ /d (@"
"$singleInstanceAccumulatorExe" -d:"" "-c:cmd /c echo `$files| pwsh.exe -noexit -noprofile -c \\"[Environment]::CommandLine; `$paths = `$input -split [char] 34 -ne ''; `$paths; Set-Clipboard `$paths\\"" "%1"
"@ -replace '"', '\"')

if ($LASTEXITCODE) { throw }

Write-Verbose -Verbose "Shortcut menu command '$menuCommandName' successfully set up."

Now you can right-click on multiple files/folders in File Explorer and select Copy Paths to Clipboard in order to copy the full paths of all selected items to the clipboard in a single operation.

---

^{[1] An alternative is to use the -f option instead, which causes SingleInstanceAccumulator.exe to write all file paths line by line to an auxiliary text file, and then expands $files to that file's full path. However, this requires the target scripts to be designed accordingly, and it is their responsibility to clean up the auxiliary text file.}