I’m trying to run a shell command with a pipe operator in it. For example “sleep 0.1 | echo foo”. At first I tried to do this with System.cmd:

System.cmd("sleep", ["0.1", "|", "echo", "foo"])

But this results in /usr/bin/sleep: invalid time interval '|', invalid time interval 'echo'....

So next I tried to use :os.cmd:

:os.cmd("sleep 0.1 | echo foo")

But whatever I do to execute this I get:

:os.cmd("sleep 0.1 | echo foo")
** (FunctionClauseError) no function clause matching in :os.validate/1    
    
    The following arguments were given to :os.validate/1:
    
        # 1
        "sleep 0.1 | echo foo"
    
    (kernel) os.erl:281: :os.validate/1
    (kernel) os.erl:237: :os.cmd/1

Looking into the code of :os (https://github.com/erlang/otp/blob/master/lib/kernel/src/os.erl) is see that :os.validate expects atoms? But in the erlang docs there are no atoms used (http://erlang.org/doc/man/os.html)