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## 9 How to Customize Traces

TRAMP messages are raised with verbosity levels ranging from 0 to 10. TRAMP does not display all messages; only those with a verbosity level less than or equal to `tramp-verbose`.

The verbosity levels are

0 silent (no TRAMP messages at all)
1 errors
2 warnings
3 connection to remote hosts (default verbosity)
4 activities
5 internal
6 sent and received strings
7 file caching
8 connection properties
9 test commands
10 traces (huge)

With `tramp-verbose` greater than or equal to 4, messages are also written to a TRAMP debug buffer. Such debug buffers are essential to bug and problem analyses. For TRAMP bug reports, set the `tramp-verbose` level to 6 (see Bug Reports).

The debug buffer is in Outline Mode. In this buffer, messages can be filtered by their level. To see messages up to verbosity level 5, enter `C-u 6 C-c C-q`.

TRAMP handles errors internally. But to get a Lisp backtrace, both the error and the signal have to be set as follows:

    (setq debug-on-error t
          debug-on-signal t)

To enable stepping through TRAMP function call traces, they have to be specifically enabled as shown in this code:

    (require 'trace)
    (dolist (elt (all-completions "tramp-" obarray 'functionp))
      (trace-function-background (intern elt)))
    (untrace-function 'tramp-read-passwd)
    (untrace-function 'tramp-gw-basic-authentication)

The buffer `*trace-output*` contains the output from the function call traces. Disable `tramp-read-passwd` and `tramp-gw-basic-authentication` to stop password strings from being written to `*trace-output*`.