# 11. Debugging

## 11.1. Dialogs

Stderr is being captured to a buffer that is being inspected at program exit. If any serious errors (tracebacks, etc) are found in the stderr buffer the entire contents are sent to the bug report tool so the user can (should) report a bug. If you suspect there are errors that are not being reported, you can set the environment variable THGDEBUG to any value to disable the stderr buffering.

If you have a bit of Python knowledge, you can also use:

    thg --debugger <command>

To disable the forking behavior of thg, you can either set an environment variable THG_HGTK_SPAWN, or add the command line parameter ‘–nofork’.

### 11.1.1. Windows

To debug the changelog viewer, for instance, enter these commands into a cmd.exe window, while inside the repository:

    set THGDEBUG=1
    thg --nofork log

### 11.1.2. Linux/MacOSX

To debug the changelog viewer, for instance, enter these commands into your shell window, while inside the repository:

    export THGDEBUG=1
    thg --nofork log

## 11.2. Shell Extension

The debugging mechanisms depend on your platform.

### 11.2.1. Windows

See also https://msdn.microsoft.com/en-us/library/cc144064(VS.85).aspx for some info bits about Running and Testing Shell Extensions on Windows

The DbgView tool from the SysInternals suite will capture debug messages from the shell extension. However, the shell extension does not emit debugging info by default. It must be enabled by setting the registry key defined in `win32/shellext/DebugShellExt.reg` in the TortoiseHg source repository. You can double-click on this file to load the key into your registry.

Another option is to exit the TortoiseHgOverlayServer system tray application and start it from the command line. It will emit some debug information to the console.

### 11.2.2. Nautilus

Debugging is done via the environment variable DEBUG_THG

- to test in a separate process:

      DEBUG_THG=Ne TMPDIR=/tmp/anydir/ --no-desktop nautilus [path]

- to test in the main instance:

      nautilus -q
      DEBUG_THG=NOe nautilus

- permanent debugging, set DEBUG_THG in a file which is read on session start (~/.profile, ~/.xprofile)

Upper case characters in DEBUG_THG specify modules. Only O and N for OverlayCache and Nautilus, respectively, are supported module names. Lower case characters imply parts. Only e is supported, implying error messages.

To restart nautilus, chose either

1. killall nautilus (the session restarts nautilus automatically, stdin and stdout go to ~/.xsession-errors)
2. nautilus -q; nautilus (stdin and stdout are on the console)