slimtoolkit/slim · error

not a terminal

Error message

not a terminal

What it means

Raised in Start (pkg/app/master/container/execution.go) when ref.options.Terminal is requested but os.Stdout is not attached to a TTY — term.GetFdInfo reports isTerminal == false. Raw-terminal mode can only be set on a real terminal, so attaching an interactive terminal session fails.

Source

Thrown at pkg/app/master/container/execution.go:294

	if ref.eventCh != nil {
		ref.eventCh <- &ExecutionEvenInfo{
			Event: XECreated,
		}
	}

	go ref.monitorContainerExitSync()

	if ref.cleanupOnSysExit {
		go ref.monitorSysExitSync()
	}

	if ref.options != nil {
		if ref.options.Terminal {
			var oldState *term.State
			var isTerminal bool
			ref.termFd, isTerminal = term.GetFdInfo(os.Stdout)
			if !isTerminal {
				return errors.New("not a terminal")
			}

			oldState, err = term.SetRawTerminal(ref.termFd)
			if err != nil {
				return err
			}

			defer term.RestoreTerminal(ref.termFd, oldState)

			ref.terminalExitChan = make(chan error)

			go ref.startTerminal()
		} else if ref.options.LiveLogs {
			go ref.startLiveLogs()
		}
	}

	if err := ref.APIClient.StartContainer(ref.ContainerID, nil); err != nil {

View on GitHub (pinned to 81940d17fa)

Solutions

1. Disable the terminal option so output streams non-interactively
2. Run the command in a real TTY (allocate a pty, e.g. docker run -t / script -c)
3. Use tools like `script` or a pty wrapper if you must keep terminal mode in automation

Example fix

// before
opts := ContainerOptions{Terminal: true}
err := ref.Start(ctx)
// after
isTTY := term.IsTerminal(int(os.Stdout.Fd()))
opts := ContainerOptions{Terminal: isTTY}
err := ref.Start(ctx)

if opts.Terminal && !term.IsTerminal(int(os.Stdout.Fd())) {
	opts.Terminal = false
}

// Go
if err := ref.Start(ctx); err != nil && err.Error() == "not a terminal" {
	// fall back to non-interactive start
}

When it happens

Trigger: Starting/exec'ing a container with terminal options enabled while stdout is a pipe, a file, or a non-interactive CI log stream.

Common situations: Running docker-slim's interactive terminal mode from CI pipelines or inside another container without -t; redirecting output to a file; running under a non-TTY docker exec.

Related errors

• Container terminated

AI-assisted analysis of slimtoolkit/slim@81940d17fa (2026-08-31). Data as JSON: /api/errors/3a660a65193cf873. Report an issue: GitHub.