It's a simple tool which allow run simple shell commands like helm install <smth> and in parallel see logs of started items kubectls logs -f -lrelease=<current-release>, in CI of cource.

Main difference from gnu parallel or xargs is that there you have one "main" command and this solution stops while "main" command stops and it return error code if "main" command fails, ignore fails of "siblings".

About error codes there are one exceptions:

• error codes may returns not from "main" command in "setup" stage, where no commands started

About messaging, it's solution redirects all command's output to stdout (stderr too) and write own messages to stderr only.

scr << EOF
timeout: 100
wait_all: false
run:
    cmd: "echo 🦁🐯"
    debug: true
watch:
    - cmd: "tail -F /dev/null"
      debug: false
      disable_time: true
      name: useless
    - cmd: "kubectl logs -f -lname=my-app"
      debug: true
      name: k8s
    - cmd: "ls -lah /var/log/"
      debug: true
      name: ls
EOF

Yep, there are few additional params - you may setup global timeout, or wait all siblings commands (in this case error codes still based on "main" cmd)

debug and name params it's about verbosity; By default messages writes with time, you may disable it with specified param disable_time: true

I think, there is no need to use many images with env + scr, so I made one scratch images and you may reuse it as:

... you stuff here

FROM c1rno/simultaneous-command-runner as scr

FROM <your working image>

COPY --from=scr /usr/local/bin/scr /usr/local/bin/scr

... you stuff here

So, use it just as carrier (alpine users may feel little butthurt).