Hi there, I was wondering if there is a way to redirect input to a system command from an elixir variable instead that from a file. In other words I’d like to invoke a command like this: wc -l < myfile using Elixir’s System.cmd: my_stream = """ a b c """ "wc" |> System.find_executable |> Syste…

That < syntax in shell is just a way to pipe the contents of a file onto the STDIN of the command. Interestingly, wc will also take a filename as a regular argument. So for either of those to work you would need to write your string to a file and use that (although I’m not sure the < would work an…

If you want pipes, you can use them. The documentation for System.cmd/2 mentions Shell commands If you desire to execute a trusted command inside a shell, with pipes, redirecting and so on, please check :os.cmd/1 . so you can do iex(11)> :os.cmd('wc -l < foo.txt') |> :binary.list_to_bin() "5\n"…

Nice, thanks for sharing that. Very cool.

Thank you. My real purpose is not to count the line of a file, it was a simplification of what I am trying to, launching an external tool via System.cmd and providing an input from STDIN. I am going to give a look to the port module, thank you

Elixir Programming Language Forum

Using elixir variable as System.cmd input

Questions & Help Questions

csuriano23 February 16, 2021, 7:41am 6

It seems a really good solution, thank you