PowerShell command line parameters and '--'

Question

For whatever reason, when I try to call a C# program I'm writing, and I try to pass two arguments with '--' in the command line, PowerShell doesn't call the program with my command line.

For instance, I'm providing the command line:

.\abc.exe foo.txt -- bar --

When I call this, the C# program's main only gets the command line arguments:

foo.txt bar --

instead of

foo.txt -- bar --

as would be expected.

Why would this be happening?

BTW, if I call it as:

.\abc.exe foo.txt '--' bar '--'

it works as expected.

Also, calling it as:

& .\abc.exe foo.txt -- bar --

Doesn't seem to help.

My reason for thinking this is a PowerShell weirdness is that if I run the same command line from CMD.EXE, everything works as expected.

a further note. apparently the two '--' isn't the whole problem. It seems that powershell dropbx the first '--' even if the second one isn't there. Seems like -- must have special meaning for powershell. — Kelly L
– Kelly L, Commented Apr 3, 2013 at 6:27

Ansgar Wiechers · Accepted Answer · 2013-04-03 13:05:20Z

17

A double hyphen instructs PowerShell to treat everything coming after as literal arguments rather than options, so that you can pass for instance a literal -foo to your script/application/cmdlet.

Example:

PS C:\> echo "-bar" | select-string -bar
Select-String : A parameter cannot be found that matches parameter name 'bar'.
At line:1 char:28
+ "-bar" | select-string -bar <<<<
    + CategoryInfo          : InvalidArgument: (:) [Select-String], ParameterBindingException
    + FullyQualifiedErrorId : NamedParameterNotFound,Microsoft.PowerShell.Commands.SelectStringCommand

vs.

PS C:\> echo "-bar" | select-string -- -bar

-bar

To avoid this behavior you must either quote ("--", '--') or escape (`--) the double hyphen.

edited Apr 3, 2013 at 13:05

answered Apr 3, 2013 at 12:58

Ansgar Wiechers

202k27 gold badges286 silver badges363 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Kelly L Over a year ago

Can you give a reference to doc somewhere that describes the purpose of '--' and how it instructs PS to do this?

Ansgar Wiechers Over a year ago

This answer from @ravikanth to a similar question cites "Windows PowerShell in Action", but other than that I don't have a source. It's consistent with other shells, though (bash for instance).

JamieSee Over a year ago

Here's a source for running executables in PowerShell that's well worth looking at: social.technet.microsoft.com/wiki/contents/articles/…

Ansgar Wiechers Over a year ago

@JamieSee I don't see the double-dash discussed in that article, only the "stop parsing" parameter (--%) that was introduced with PowerShell v3.

Mariusz Pawelski Over a year ago

I anyone is looking for the official docs about this -- feature, here it is.

Peter Mortensen · Accepted Answer · 2019-03-22 20:57:15Z

10

With PowerShell 3 you can use --% to stop the normal parsing PowerShell does.

.\abc.exe --% foo.txt -- bar --

edited Mar 22, 2019 at 20:57

Peter Mortensen

31.4k22 gold badges110 silver badges134 bronze badges

answered May 4, 2013 at 16:21

Lars Truijens

43.9k6 gold badges134 silver badges146 bronze badges

Collectives™ on Stack Overflow

PowerShell command line parameters and '--'

2 Answers 2

5 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

5 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related