Rsyslog provides a number of debug aids. Some of them are activated by
adding the --enable-rtinst ./configure option ("rtinst" means runtime
instrumentation). Turning debugging on obviously costs some performance
(in some cases considerable).
This is document is just being created and thus terse.
Signals supported
SIGUSR1 - turns debug messages on and off (expect this signal
to go away over time)
SIGUSR2 - outputs debug information (including active threads
and a call stack) for the state when SIGUSR2 was received. This is a
one-time output. Can be sent as often as the user likes.
Environment Variables
There are two environment variables that set several debug settings. The "RSYSLOG_DEBUGLOG" (sample: RSYSLOG_DEBUGLOG="/path/to/debuglog/")
writes (allmost)
all debug message to the specified log file in addition to stdout. Some
system messages (e.g. segfault or abort message) are not written to the
file as we can not capture them. Runtime debug support is controlled by
"RSYSLOG_DEBUG". It contains an option string with the following
options possible (all are case insensitive):
LogFuncFlow - print out the logical flow of functions (entering and exiting them)
FileTrace - specifies which files to trace LogFuncFlow. If not
set (the default), a LogFuncFlow trace is provided for all files. Set
to limit it to the files specified. FileTrace may be specified multiple
times, one file each (e.g. export RSYSLOG_DEBUG="LogFuncFlow
FileTrace=vm.c FileTrace=expr.c"
PrintFuncDB - print the content of the debug function database whenever debug information is printed (e.g. abort case)!
PrintAllDebugInfoOnExit - print all debug information immediately before rsyslogd exits (currently not implemented!)
PrintMutexAction - print mutex action as it happens. Useful for finding deadlocks and such.
NoLogTimeStamp - do not prefix log lines with a timestamp (default is to do that).
NoStdOut - do not emit debug messages to stdout. If RSYSLOG_DEBUGLOG is not set, this means no messages will be displayed at all.
help - display a very short list of commands - hopefully a life saver if you can't access the documentation...
