4.1.10 filters statement

The filters statement configures user-defined external filters. See Filters, for the detailed discussion of external filters.

Syntax

filters {
        filter ident {
                exec-path path ;
                error-log filename ;
                common bool [max-wait];
                auth {
                        input-format fmt ;
                        wait-reply bool ;
                };
                acct {
                        input-format fmt ;
                        wait-reply bool ;
                };
        };
        …
};

Each filter directive defines a new filter. The ident argument declares the name of the filter. This string must be used in Exec-Program-Wait or Acct-Ext-Program attributes to trigger invocation of this filter (see Exec-Program-Wait).

Usage

exec-path path

Absolute path to the filter program.

error-log filename

Redirect error output from the filter program to filename. If the filename does not start with a slash, it is taken relative to the current logging directory (see log-dir).

auth

acct

These compound statements define authentication and accounting parts of this filter. Any one of them may be missing. The two statements allowed within auth and acct blocks are:

input-format fmt

Format of the input line for this filter. Usually this string uses %C{} notations (see Macro Substitution).

You can also use the return value from a rewrite function as input line to the filter. To do so, declare:

        input-format "=my_func()";

where my_func is the name of the rewrite function to invoke. The function must return string value.

wait-reply bool

If the filter prints a single line of output for each input line, set this to yes. Otherwise, if the filter produces no output, use wait-reply no.