## Running GLib Applications

Running GLib Applications — How to run and debug your GLib application

## Running and debugging GLib Applications

### Environment variables

GLib inspects a few of environment variables in addition to standard variables like `LANG`, `PATH` or `HOME`.

`G_FILENAME_ENCODING`. This environment variable can be set to a comma-separated list of character set names. GLib assumes that filenames are encoded in the first character set from that list rather than in UTF-8. The special token "@locale" can be used to specify the character set for the current locale.

`G_BROKEN_FILENAMES`. If this environment variable is set, GLib assumes that filenames are in the locale encoding rather than in UTF-8. G_FILENAME_ENCODING takes priority over G_BROKEN_FILENAMES.

`G_MESSAGES_PREFIXED`. A list of log levels for which messages should be prefixed by the program name and PID of the application. The default is to prefix everything except `G_LOG_LEVEL_MESSAGE` and `G_LOG_LEVEL_INFO`.

`G_DEBUG`. If GLib has been configured with `--enable-debug=yes`, this variable can be set to a list of debug options, which cause GLib to print out different types of debugging information.

fatal_warnings | Causes GLib to abort the program at the first call to g_warning(). This option is special in that it doesn't require GLib to be configured with debugging support.

`G_RANDOM_VERSION`. If this environment variable is set to '2.0', the outdated pseudo-random number seeding and generation algorithms from GLib-2.0 are used instead of the new better ones. Use the GLib-2.0 algorithms only if you have sequences of numbers generated with Glib-2.0 that you need to reproduce exactly.

`LIBCHARSET_ALIAS_DIR`. Allows to specify a nonstandard location for the `charset.aliases` file that is used by the character set conversion routines. The default location is the `libdir` specified at compilation time.

`G_WIN32_PRETEND_WIN9X`. Setting this variable to any value forces g_win32_get_windows_version() to return a version code for Windows 9x. This is mainly an internal debugging aid for GTK+ and GLib developers, to be able to check the code paths for Windows 9x.

### Traps and traces

Some code portions contain trap variables that can be set during debugging time if GLib has been configured with `--enable-debug=yes`. Such traps lead to immediate code halts to examine the current program state and backtrace.

Currently, the following trap variables exist:

    static volatile gulong g_trap_free_size;
    static volatile gulong g_trap_realloc_size;
    static volatile gulong g_trap_malloc_size;

If set to a size > 0, g_free(), g_realloc() and g_malloc() will be intercepted if the size matches the size of the corresponding memory block. This will only work with `g_mem_set_vtable (glib_mem_profiler_table)` upon startup though, because memory profiling is required to match on the memory block sizes.