16.7. Chaining Filters

If a filter command has a pipe (|) or IO redirection indicator (< or >) in it, or starts with an open parenthesis ((), the filter is run by passing the entire command to the shell specified by the shell configuration option. This allows a wide variety of options and operations to be carried out. The $* value should be used to have the filter options passed to the correct entry in the filter chain.

For example,

    lp:
      :filter=( echo "starting `date`" >/var/log/status; /usr/local/ifhp $* )