25.4.2. Compatibility with sysklogd

The compatibility mode specified via the -c option exists in rsyslog version 5 but not in version 7. Also, the sysklogd-style command-line options are deprecated and configuring rsyslog through these command-line options should be avoided. However, you can use several templates and directives to configure rsyslogd to emulate sysklogd-like behavior.
For more information on various rsyslogd options, see the rsyslogd(8)manual page.