CODEWITHSUNDEEP
elixirphoenix-framework
Karolis
Karolis

Reputation: 534

How to run System.cmd in parallel

I want to start these two commands in mix task:

System.cmd("cmd.exe", ["/c", "mix phx.server"], into: IO.stream(:stdio, :line))
System.cmd("cmd.exe", ["/c", "npm run dev"], cd: ".\\frontend", into: IO.stream(:stdio, :line))

However, both of them are blocking therefore, despite the order, second one never gets executed. How do I start both of them at once?

Upvotes: 0

Views: 263

Answers (1)

Aleksei Matiushkin
Aleksei Matiushkin

Reputation: 121000

While the comment above by @sabiwara is absolutely correct, I am to address the exact problem stated explicitly.

One might use Task.async/1 or even just spawn/3:

spawn(
  System, 
  :cmd,
  ["cmd.exe", ["/c", "mix phx.server"], into: IO.stream(:stdio, :line)]
)
spawn(
  System,
  :cmd, 
  ["cmd.exe", ["/c", "npm run dev"],
    cd: ".\\frontend", into: IO.stream(:stdio, :line)]
)

Upvotes: 2

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