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I have this PowerShell script that I want to run for my angular project.
I can only get it to run the first command or I can only get it to run the first command and then immediately run the second command.

Start /wait /b   rmdir  node_modules /S
 
 Start npm install /b /wait

I've looked on stack overflow and googled different stuff and have seen some good suggestions but haven't been able to get it to work correctly. It does currently run the first command and then finish.

I've tried to remove some of the parameters like /b or /S with no luck.

R. Richards
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RedProject
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  • `Remove-Item node_modules -Force -Recurse; Start-Process npm install -Wait` – Mathias R. Jessen Nov 23 '22 at 14:59
  • If you need an answer in general (unrelated to npm) then a solution is to write your own function to invoke process, process class has `WaitForExit` which let's you wait for process to finish, see https://learn.microsoft.com/en-us/dotnet/api/system.diagnostics.process?view=net-7.0 – metablaster Nov 23 '22 at 15:02
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    Why are you using `Start`(`-Process`) at all? – iRon Nov 23 '22 at 15:03

1 Answers1

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  • Your primary problem is that you're using syntax for cmd.exe's internal start and rmdir commands, which doesn't work in PowerShell.

    • While PowerShell does have commands with the same names, they're aliases of PowerShell cmdlets, Start-Process and Remove-Item, and therefore require different syntax.

  • While you could fix your Start commands to use Start-Process instead, there's no reason to use it to begin with, given that invoking cmdlets and (console) programs directly executes them synchronously, in the same console window, with the output streams connected to PowerShell's, by default.

Therefore:

Remove-Item -Force -Recurse node_modules  # Equivalent of rmdir /S /Q node_modules
npm install

Note: In older versions of Windows, including versions of Windows 10 prior to release 20H2, file and directory removal is inherently asynchronous, so on occasion the removal may not have fully completed yet by the time Remove-Item returns; it seems that calling via cmd /c - cmd /c rmdir /S /Q node_modules - lessens the chances of that happening (but still doesn't fully eliminate the problem). A reliable workaround is far from trivial, unfortunately - see this answer.

Update: As it turns out, you were actually running a batch file (.cmd or .bat), not a PowerShell script (.ps1), but the above points apply analogously; the batch-file solution is:

rmdir /S /Q node_modules
npm install
mklement0
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  • Thank you i changed Remove-Item to rmdir because it was a syntax error but other than that this solution worked great. – RedProject Nov 23 '22 at 18:05
  • Glad to hear it, @RedProject. If the `Remove-Item` call caused a syntax error and `rmdir` worked _without `cmd /c`_, the implication is that you're running a _batch file_ (`.cmd` or `.bat`), not a PowerShell script (`.ps1`). – mklement0 Nov 23 '22 at 18:10
  • Thanks sorry for the miscommunication. – RedProject Nov 23 '22 at 18:59