Hi there, I’m having some trouble with the “System” module, specifically the cmd function. My code is the following, which is exactly the same as the documentation, StackOverflow/Elixir forum answers, etc: System.cmd("echo", ["Hello"]) I’m getting the following error: ** (ErlangError) Erlang erro…

In windows echo as well as dir are strict built-in a, there is no way to call them as binary. You probably need to do something like System.cmd("cmd", ["-c", "echo foo"]) or something like that.

The function requires a binary (string with double quotes) and not a charlist (string with single quotes). That’s is the argument error that you’re getting. :os.cmd is the Erlang equivalent function. Are you using Windows or a Unix-like OS?

:os.cmd use a shell while System.Cmd doesn’t. In a Unix like os, echo is both a shell builtin and an external command as /bin/echo so both should work. Like the other replier guessed you probrably don’t have /bin/echo

I’m using Windows, probably shouldv’e mentioned it. However, echo does work in windows, no? I also tried dir just in case, and it didn’t work either

Could you point me to the relevant resources or search terms? At this point I’m not sure what to look for in this case

Back in the days, MS-DOS came with a good help program, very close to man on unix systems, but for actual DOS tools and builtins only. Not sure if this is still available in todays cmd.exe, but to be honest, I doubt it is… With a bit of luck there is some /help or --help switch for cmd.exe that you…

Yes, by calling Powershell instead of cmd and passing it the command/script with appropriate command line flags.

The first thing I do on Windows is to install msys2 which gives you a sane command line interface. Cmd is dead. PowerShell is nice however it is not significantly better than bash so I don’t see the point of being different from everybody else.

Elixir Programming Language Forum

Error when using System.cmd

Questions & Help Questions

HaydenAscot August 9, 2020, 12:09pm 8

is it possible to run PowerShell commands from Elixir instead?