Run a shell command with arguments from powershell script

Question

I need to extract and save a some tables from a remote SQL database using bcp. I would like to write a powershell script to invoke bcp for each table and save the data. So far I have this script that creates the necessary args for bcp. However I can not figure out how to pass the args to bcp. Every time I run the script it just shows the bcp help instead. This must be something really easy that I am not getting.

#commands bcp database.dbo.tablename out c:\temp\users.txt -N -t, -U uname -P pwd -S <servername>
$bcp_path = "C:\Program Files\Microsoft SQL Server\90\Tools\Binn\bcp.exe"
$serverinfo =@{}
$serverinfo.add('table','database.dbo.tablename')
$serverinfo.add('uid','uname')
$serverinfo.add('pwd','pwd')
$serverinfo.add('server','servername')
$out_path= "c:\Temp\db\"
$args = "$($serverinfo['table']) out $($out_path)test.dat -N -t, -U $($serverinfo['uid']) -P $($serverinfo['pwd']) -S $($serverinfo['server'])"

#this is the part I can't figure out
& $bcp_path $args

Answer 1

First of all, $args is an automatic variable; you can't set it, so any line like $args = foo will do nothing (even with strict mode on; though a complaint would have been nice).

Then you are only passing a single argument (the string) to the program. I contains spaces, but they are properly escaped or enclosed in parentheses, so the program only sees a single argument.

You'll need to use an array for arguments to a program, instead of a single string, if you want to store it in a variable beforehand. And you need to name it something different than $args:

$arguments = "$($serverinfo['table'])",
             'out',"$($out_path)test.dat",
             '-N','-t,',
             '-U',"$($serverinfo['uid'])",
             '-P',"$($serverinfo['pwd'])",
             '-S',"$($serverinfo['server'])"

& $bcp_path $arguments

Or, what I would prefer, actually, you can simply write it out in a single line which gets rid of most of the ugliness here:

$out_path = 'c:\Temp\db'
& $bcp_path $serverinfo['table'] out $out_path\test.dat -N '-t,' -U $serverinfo['uid'] -P $serverinfo['pwd'] -S $serverinfo['server']

Answer 2

Some command-line apps that need to accept crazy Gangnam-style arguments with slashes, quotes, double-quotes, equals, colons, dashes, a veritable cocktail.

PowerShell, in my experience, sometimes just can't cope. So I write out to a .cmd file and execute that from cmd.exe, like so:

echo $("Running command: " + $commandLine);

$rnd = $(([string](Get-Random -Minimum 10000 -Maximum 99999999)) + ".cmd");
$commandFilePath = $(Join-Path -Path $env:TEMP -ChildPath $rnd);
echo $commandLine | Out-File -FilePath $commandFilePath -Encoding ascii;

& cmd.exe /c $commandFilePath

Make sure you output as ASCII since the default Unicode might not play nice with cmd.exe (it barked at me and showed odd characters on my first attempt).