What causes "tailing log file: %w" in wavetermdev/waveterm?

Check the file exists and is readable: `ls -l ` and `tail -c 1k `.

tailing log file: %w

Error message

tailing log file: %w

What it means

This wraps any error from tailLogFile, the local routine that reads and streams the last 16KB (and then follows) the log file. The RPC succeeded and returned a path, but local file access or stat/seek/read failed; the cause is preserved.

Source

Thrown at cmd/wsh/cmd/wshcmd-wavepath.go:77

	tabId := getTabIdFromEnv()
	if tabId == "" {
		return fmt.Errorf("no WAVETERM_TABID env var set")
	}

	path, err := wshclient.PathCommand(RpcClient, wshrpc.PathCommandData{
		PathType:     pathType,
		Open:         open,
		OpenExternal: openExternal,
		TabId:        tabId,
	}, nil)
	if err != nil {
		return fmt.Errorf("getting path: %w", err)
	}

	if tail && pathType == "log" {
		err = tailLogFile(path)
		if err != nil {
			return fmt.Errorf("tailing log file: %w", err)
		}
		return nil
	}

	WriteStdout("%s\n", path)
	return nil
}

func tailLogFile(path string) error {
	file, err := os.Open(path)
	if err != nil {
		return fmt.Errorf("opening log file: %w", err)
	}
	defer file.Close()

	// Get file size
	stat, err := file.Stat()
	if err != nil {

View on GitHub (pinned to a4447c1563)

Solutions

Check the file exists and is readable: `ls -l <path>` and `tail -c 1k <path>`.
Fix permissions on the Wave log directory or run as the user who owns the terminal.
Re-run the command to pick up a fresh path after log rotation.
If tailing isn't essential, use `wsh wavepath log` without --tail.

Example fix

// before
err = tailLogFile(path) // fails on rotated file
// after
if _, err := os.Stat(path); os.IsNotExist(err) { path, err = refreshLogPath() }

Defensive patterns

Strategy: retry

Validate before calling

logpath=$(wsh wavepath log) && [ -r "$logpath" ] && [ -f "$logpath" ] || exit 1

Try / catch

err := tailLogFile(path)
if err != nil {
    time.Sleep(500 * time.Millisecond)
    if retryErr := tailLogFile(path); retryErr != nil { return fmt.Errorf("tailing log file: %w", retryErr) }
}

Prevention

Re-fetch the path after log rotation instead of reusing old paths.
Check readability/permissions of the Wave log directory.
Prefer plain `wsh wavepath log` when only the path is needed.

When it happens

Trigger: `wsh wavepath log --tail` where the returned log path cannot be opened, stat'ed, seeked, or read (file deleted, rotated away, permission denied, or path points to a non-regular file).

Common situations: Log rotation removing the file between RPC and tail, running wsh as a user without read access to Wave's log dir, or log path on an unmounted volume.

Understand the failure class

Background: "open() failed", "failed to open file", "cannot create file" — what a file open error means and how to fix it — this error's family across 42 libraries.

Related errors

AI-assisted analysis of wavetermdev/waveterm@a4447c1563 (2026-09-01). Data as JSON: /api/errors/6dca992167bd6a1a. Report an issue: GitHub.