Powershell: Start-Process with a file variable

Question

c:\test.ps1 exists and is an empty file.

Start-Process -filepath powershell -argumentlist { -noexit -file "c:\test.ps1" }

opens a new powershell window and keeps it open (which is what I want).

$a = "c:\test.ps1"
Start-Process -filepath powershell -argumentlist { -noexit -file "$a" }

briefly flashes a new Powershell window and then closes it immediately. I wonder why?

Good point re script blocks, @MathiasR.Jessen, but I suggest always recommending a single string that encodes all arguments, for the reasons stated in my answer. For instance - as unfortunate as that is - if $a happens to contain a path with spaces, -ArgumentList '-noexit', '-file', $a fails. — mklement0
– mklement0, Commented Jun 21, 2021 at 13:29

mklement0 · Accepted Answer · 2025-04-12 16:36:01Z

tl;dr

To pass pass-through arguments to Start-Process's -ArgumentList (-Args) parameter:

Do NOT use a script block ({ ... }).
DO use a single, expandable string ("..."):

$a = "c:\test.ps1"
Start-Process powershell "-noexit -file `"$a`""

^{Note: Parameter names -FilePath and -ArgumentList are positionally implied in this command; that is, the command is equivalent to Start-Process -FilePath powershell -ArgumentList "-noexit -file `"$a`""}

As for what you tried:

Start-Process's -ArgumentList (-Args) parameter is [string[]] typed, i.e. it expects an array of string arguments to pass to the external program being launched - given that strings are the only supported data type when passing arguments to external programs.

Note: While passing pass-through arguments individually to -ArgumentList, as the elements of an array (-ArgumentList '-noexit', '-file', $a), may conceptually be preferable, it is unfortunately marred by a long-standing bug in Start-Process that will not be fixed as such, so as not to break backward compatibility - see GitHub issue #5576; in short, array elements that (may) contain spaces must unexpectedly be enclosed in embedded double quotes (-ArgumentList '-noexit', '-file', "`"$a`"")
For now, using a single string that encodes all arguments, each enclosed in embedded "..." quoting if necessary (as shown above), is therefore preferable.
As discussed in the linked GitHub issue, an alternative -ArgumentArray parameter that supports robust array-based argument passing may be introduced in the future.

When you pass a script block ({ ... }), it is stringified (its .ToString() method is implicitly called), and a script block's stringification is its verbatim contents (excluding the enclosing { and }), which means that no expansion (string interpolation) takes place;
try { $HOME }.ToString(), for instance.

Note: You can use script blocks when you invoke powershell.exe directly, synchronously (rather than via Start-Process), but only from PowerShell, and such script blocks are executed by the callee, and therefore also do not see the caller's variables; you can, however, pass arguments to them; e.g.:
powershell { "args passed: $args" } -args 1, 2

Berend Engelbrecht · Accepted Answer · 2024-09-05 05:04:35Z

0

A good way to pass the Start-Process argument list is:

-argumentlist @("argument1", "argument2", ...)

This syntax makes use of the fact that ArgumentList by default expects a string array:

Start-Process
     [-FilePath] <string>
     [[-ArgumentList] <string[]>]

answered Sep 5, 2024 at 5:04

Berend Engelbrecht

1,48716 silver badges12 bronze badges

2 Comments

mklement0 Apr 12 at 16:39

While passing pass-through arguments individually to -ArgumentList, as the elements of an array may conceptually be preferable, it is unfortunately marred by a long-standing bug in Start-Process that will not be fixed as such, so as not to break backward compatibility; in short, array elements that (may) contain spaces must unexpectedly be enclosed in embedded double quotes (-ArgumentList '-noexit', '-file', "`"$a`"").

mklement0 Apr 12 at 16:39

For now, using a single string that encodes all arguments, each enclosed in embedded "..." quoting if necessary (-ArgumentList "-noexit -file `"$a`""), is therefore preferable. As discussed in the original bug report, GitHub issue #5576, an alternative -ArgumentArray parameter that supports robust array-based argument passing may be introduced in the future.

Collectives™ on Stack Overflow

Powershell: Start-Process with a file variable

2 Answers 2

Comments

2 Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

2 Comments

Linked

Related