running shell commands crystal language and capturing the output - crystal-lang

Question

I am used to using open3 to run commands in Ruby. Since there doesn't seem to be an equivalent lib in crystal-lang, I kludged up this:
def run_cmd(cmd, args)
stdout_str = IO::Memory.new
stderr_str = IO::Memory.new
result = [] of Int32 | String
status = Process.run(cmd, args: args, output: stdout_str, error: stderr_str)
if status.success?
result = [status.exit_code, "#{stdout_str}"]
else
result = [status.exit_code, "#{stderr_str}"]
end
stdout_str.close
stderr_str.close
result
end
cmd = "ping"
hostname = "my_host"
args = ["-c 2", "#{hostname}"]
result = run_cmd(cmd, args)
puts "ping: #{hostname}: Name or service not known" if result[0] != 0
Is there a better way to do this? Says the retired network specialist who is not a software developer exploring crystal-lang.
Thanks in advance for all advice.

Answer 1

Probably this:
def run_cmd(cmd, args)
stdout = IO::Memory.new
stderr = IO::Memory.new
status = Process.run(cmd, args: args, output: stdout, error: stderr)
if status.success?
{status.exit_code, stdout.to_s}
else
{status.exit_code, stderr.to_s}
end
end
We don't need to close an IO::Memory because it doesn't represent a handle to any OS resources, just a block of memory, and we use tuples instead of arrays for the return. This means the callers know we're returning exactly two items and the first is a number and the second is a string. With an array return the caller only knows we're returning any number of items, any of which could be either an int32 or a string.
You can then use it like this:
cmd = "ping"
hostname = "my_host"
args = ["-c 2", hostname]
status, output = run_cmd(cmd, args)
puts "ping: #{hostname}: Name or service not known" unless status == 0