Prototype: filter(filter, list, is_regex, invert, max_return)

Return type: slist

Description: Transforms a list into a subset thereof.

This is a generic filtering function that returns a list of up to max_return elements in list that match the filtering rules specified in filter, is_regex and invert.


  • filter : Anchored regular expression or static string to find, in the range .*
  • list : The name of the list variable to check, in the range [a-zA-Z0-9_$(){}\[\].:]+
  • is_regex_ : Boolean

Treat filter as a regular expression or as a static string.

  • invert : Boolean

Invert filter.

  • max_return : Maximum number of elements to return in the range 0,999999999


    bundle agent test
          "test" slist => {
                            "one", "two", "three",
                            "long string",
                            "one", "two", "three",

          "test_grep" slist => filter("[0-9]", "test", "true", "false", 999);
          "test_exact1" slist => filter("one", "test", "false", "false", 999);
          "test_exact2" slist => filter(".", "test", "false", "false", 999);
          "test_invert" slist => filter("[0-9]", "test", "true", "true", 999);
          "test_max2" slist => filter(".*", "test", "true", "false", 2);
          "test_max0" slist => filter(".*", "test", "true", "false", 0);
          "grep" slist => grep("[0-9]", "test");

          "The test list is $(test)";
          "The grepped list is $(grep)";
          "The filter-grepped list is $(test_grep)";
          "The filter-exact list, looking for 'one' is $(test_exact1)";
          "This line should not appear: $(test_exact2)";
          "The filter-invert list, looking for non-digits, is $(test_invert)";
          "The filter-bound list, matching at most 2 items, is $(test_max2)";
          "This line should not appear: $(test_max0)";

See also: grep(), every(), some(), and none().