powershell sending multiple parameter to a external command - powershell

Question

I am trying to run a external exe from a powershell script.
This exe wants 4 parameters.
I have been trying every combo of invoke-item, invoke-command, & 'C:\program files\mycmd.exe myparam', made a shortcut in C:\ to get rid of the spaces in the path.
I can make it work with one parameter, but not with more. I get various errors.
To sum up, how do you send 4 parameters to an exe?

Answer 1

It's best if shown in longhand. Once you see what's going on, you can shorten it down by just using commas between each argument.
$arg1 = "filename1"
$arg2 = "-someswitch"
$arg3 = "C:\documents and settings\user\desktop\some other file.txt"
$arg4 = "-yetanotherswitch"
$allArgs = #($arg1, $arg2, $arg3, $arg4)
& "C:\Program Files\someapp\somecmd.exe" $allArgs
... shorthand:
& "C:\Program Files\someapp\somecmd.exe" "filename1", "-someswitch", "C:\documents and settings\user\desktop\some other file.txt", "-yetanotherswitch"

Answer 2

In the easy case, passing arguments to a native exe is as simple as using a built-in command:
PS> ipconfig /allcompartments /all
You can run into problems when you specify a full path to an EXE and that path contains spaces. For example if PowerShell sees this:
PS> C:\Program Files\Microsoft SDKs\Windows\v7.0\Bin\sn.exe -k .\pubpriv.snk
It interprets the command to be "C:\Program" and "Files\Microsoft" as the first parameter, "SDKs\Windows\v7.0\Bin\sn.exe" as the second parameter, etc. The simple solution is to put the path in a string use the invocation operator & to invoke the command named by the path e.g.:
PS> & 'C:\Program Files\Microsoft SDKs\Windows\v7.0\Bin\sn.exe' -k .\pubpriv.snk
The next area we run into problems with is when the arguments are complex and/or use characters that PowerShell interprets specially e.g.:
PS> sqlcmd -v user="John Doe" -Q "select '$(user)' as UserName"
This doesn't work and we can debug this by using a tool from the PowerShell Community Extensions called echoargs.exe which shows you exactly how the native EXE receives the arguments from PowerShell.
PS> echoargs -v user="John Doe" -Q "select '$(user)' as UserName"
The term 'user' is not recognized as the name of a cmdlet, function,
script file, or operable program. Check the spelling of the name, ...
<snip>
Arg 0 is <-v>
Arg 1 is <user=John Doe>
Arg 2 is <-Q>
Arg 3 is <select '' as UserName>
Note that with Arg3 $(user) is interpreted & evaluated by PowerShell and results in an empty string. You can fix this problem and a good number of similar issues by using single quotes instead of double qoutes unless you really need PowerShell to evaluate a variable e.g.:
PS> echoargs -v user="John Doe" -Q 'select "$(user)" as UserName'
Arg 0 is <-v>
Arg 1 is <user=John Doe>
Arg 2 is <-Q>
Arg 3 is <select $(user) as UserName>
If all else fails, use a here string and Start-Process like so:
PS> Start-Process echoargs -Arg #'
>> -v user="John Doe" -Q "select '$(user)' as UserName"
>> '# -Wait -NoNewWindow
>>
Arg 0 is <-v>
Arg 1 is <user=John Doe>
Arg 2 is <-Q>
Arg 3 is <select '$(user)' as UserName>
Note if you are using PSCX 1.2 you will need to prefix Start-Process like so - Microsoft.PowerShell.Management\Start-Process to use PowerShell's built-in Start-Process cmdlet.