go-delve/delve · error

redirect error: %s redirected twice

Error message

redirect error: %s redirected twice

What it means

parseOneRedirect extracts stdin/stdout/stderr redirections (<, >, 2>) from the tail of a restart command line, storing each target in a [3]string. Each stream may be redirected at most once; if the same prefix appears twice (already recorded in redirs[i]), the command is rejected with 'redirect error: %s redirected twice'.

Source

Thrown at pkg/terminal/command.go:1322

			break
		}
	}
	return true, w, redirs, nil
}

func parseOneRedirect(w []string, redirs *[3]string) ([]string, bool, error) {
	prefixes := []string{"<", ">", "2>"}
	names := []string{"stdin", "stdout", "stderr"}
	if len(w) >= 2 {
		if slices.Contains(prefixes, w[len(w)-2]) {
			w[len(w)-2] += w[len(w)-1]
			w = w[:len(w)-1]
		}
	}
	for i, prefix := range prefixes {
		if strings.HasPrefix(w[len(w)-1], prefix) {
			if redirs[i] != "" {
				return nil, false, fmt.Errorf("redirect error: %s redirected twice", names[i])
			}
			redirs[i] = w[len(w)-1][len(prefix):]
			return w[:len(w)-1], true, nil
		}
	}
	return w, false, nil
}

func printcontextNoState(t *Term) {
	state, _ := t.client.GetState()
	if state == nil || state.CurrentThread == nil {
		return
	}
	printcontext(t, state)
}

func (c *Commands) rebuild(t *Term, ctx callContext, args string) error {
	if ctx.Prefix == revPrefix {

View on GitHub (pinned to a23773e6c3)

Solutions

1. Keep at most one redirect per stream: `restart prog > out.txt` not `> a > b`.
2. Merge the two targets: pick the single file you actually want per stream.
3. Remember stdin has only one '<'; stderr only one '2>' per command line.
4. If you need append behavior, this parser does not support `>>`; write to a fresh file or handle appending outside Delve.

Example fix

// before
restart myprog > out.log > out2.log
// error: redirect error: stdout redirected twice

// after
restart myprog > out.log

// Ensure each redirect prefix appears at most once before invoking restart
func hasDuplicateRedirects(args string) bool {
    for _, p := range []string{"<", ">", "2>"} {
        if strings.Count(args, p) > 1 {
            return true
        }
    }
    return false
}
// if hasDuplicateRedirects(args) { fix args first }

if err := cmd.Execute("restart "+args); err != nil {
    if strings.Contains(err.Error(), "redirected twice") {
        fmt.Fprintln(os.Stderr, "each of stdin/stdout/stderr may be redirected at most once")
    }
}

When it happens

Trigger: `restart prog > a > b` or `restart prog < in1 < in2` or `restart prog 2> x 2> y` — the same stream prefix encountered twice in parseNewArgv's redirect-extraction loop.

Common situations: Users assume shell-like `>>` appending or chaining works and write `> file1 > file2`; scripted restart commands built programmatically concatenate two redirect specs; copy-pasting a shell command line that legitimately redirects a stream twice.

Related errors

• illegal commandline '%s'
• command not available
• unknown config parameter
• address required
• Process %d has exited with status %d

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/14686a8c1a4d9f84. Report an issue: GitHub.