pranshuparmar/witr · warning

process %d not found

Error message

process %d not found

What it means

After a successful ps run, FreeBSD ReadProcess requires a non-empty output line; an empty line means ps matched nothing — effectively 'process not found' with a zero exit code. It is separated from the wrapped-error path because the underlying exec error is unavailable.

Source

Thrown at internal/proc/process_freebsd.go:40

	}
	pidStr := strconv.Itoa(pid)

	// Format: pid(0) ppid(1) uid(2) jid(3) state(4) pcpu(5) rss(6) lstart(7-11) args(12+)
	// comm is excluded because it can contain spaces, which breaks strings.Fields parsing.
	// The display name is derived from args instead.
	cmd := exec.Command("ps", "-p", pidStr,
		"-o", "pid=", "-o", "ppid=", "-o", "uid=", "-o", "jid=",
		"-o", "state=", "-o", "pcpu=", "-o", "rss=",
		"-o", "lstart=", "-o", "args=")
	cmd.Env = buildEnvForPS()
	out, err := cmd.Output()
	if err != nil {
		return model.Process{}, fmt.Errorf("process %d not found: %w", pid, err)
	}

	line := strings.TrimSpace(string(out))
	if line == "" {
		return model.Process{}, fmt.Errorf("process %d not found", pid)
	}

	fields := strings.Fields(line)
	if len(fields) < 12 {
		return model.Process{}, fmt.Errorf("unexpected ps output format for pid %d: got %d fields in %q", pid, len(fields), line)
	}

	ppid, _ := strconv.Atoi(fields[1])
	uid, _ := strconv.Atoi(fields[2])
	jid := fields[3]
	state := fields[4]
	cpuPct, _ := strconv.ParseFloat(fields[5], 64)
	rssKB, _ := strconv.ParseFloat(fields[6], 64)

	lstartStr := strings.Join(fields[7:12], " ")
	startedAt := parseLstart(lstartStr)
	if startedAt.IsZero() {
		startedAt = time.Now().UTC()

View on GitHub (pinned to dc4fa1da82)

Solutions

1. Confirm the PID exists with an independent `ps -p <pid>`; treat empty output as process-not-found.
2. Retry once quickly; persistent emptiness means the process is gone.
3. Check jail/container visibility if the PID is known to be alive from another vantage point.
4. Look for PID reuse: re-fetch the PID from the source that reported it.

out, err := exec.Command("ps", "-p", strconv.Itoa(pid)).Output()
if err != nil || len(strings.TrimSpace(string(out))) == 0 {
    // no rows: process gone or not visible in this jail
}

proc, err := proc.ReadProcess(pid)
if err != nil {
    if strings.Contains(err.Error(), "process "+pidStr+" not found") && !strings.Contains(err.Error(), ": %") {
        // empty output path: handle as process-not-found
    }
}

When it happens

Trigger: ReadProcess on a PID that ps resolves to zero output rows — the process exited during the ps call, or a visibility edge where ps exits 0 with no match.

Common situations: Racing very short-lived processes; ps behavior differences inside jails; stale PID from a cache.

Related errors

• process %d not found: %w
• process %d not found: %w
• process %d not found
• process %d not found in snapshot
• invalid pid %d

AI-assisted analysis of pranshuparmar/witr@dc4fa1da82 (2026-09-01). Data as JSON: /api/errors/c19480416012ee5f. Report an issue: GitHub.