vars

Variables in CFEngine are defined as promises that an identifier of a certain type represents a particular value. Variables can be scalars or lists of types string, int or real. Arrays are associative and use square brackets [] to enclose an-arbitrary key.

Scalar Variables

string

Description: A scalar string

Type: string

Allowed input range: (arbitrary string)

Example:

    vars:

     "xxx"    string => "Some literal string...";
     "yyy"    string => readfile( "/home/mark/tmp/testfile" , "33" );

int

Description: A scalar integer

Type: int

Allowed input range: -99999999999,9999999999

Example:

    vars:

     "scalar" int    => "16k";
     "ran"    int    => randomint(4,88);
     "dim_array" int =>  readstringarray("array_name","/etc/passwd","#[^\n]*",":",10,4000);

Notes:

Int variables are strings that are expected to be used as integer numbers. The typing in CFEngine is dynamic, so the variable types are interchangeable. However, when you declare a variable to be type int, CFEngine verifies that the value you assign to it looks like an integer (e.g., 3, -17, 16K).

real

Description: A scalar real number

Type: real

Allowed input range: -9.99999E100,9.99999E100

Example:

    vars:

     "scalar" real   => "0.5";

Notes:

Real variables are strings that are expected to be used as real numbers. The typing in CFEngine is dynamic, so the variable types are interchangeable, but when you declare a variable to be type real, CFEngine verifies that the value you assign to it looks like a real number (e.g., 3, 3.1415, .17, 6.02e23, -9.21e-17).

Real numbers are not used in many places in CFEngine, but they are useful for representing probabilities and performance data.

List variables

Lists are specified using curly brackets {} that enclose a comma-separated list of values.

slist

Description: A list of scalar strings

Type: slist

Allowed input range: (arbitrary string)

Example:

    vars:

     "xxx"    slist  => {  "literal1",  "literal2" };
     "yyy"    slist  => { 
                        readstringlist(
                                      "/home/mark/tmp/testlist",
                                      "#[a-zA-Z0-9 ]*",
                                      "[^a-zA-Z0-9]",
                                      15,
                                      4000
                                      ) 
                        };

     "zzz"    slist  => { readstringlist("/home/mark/tmp/testlist2","#[^\n]*",",",5,4000) };

Notes:

Some functions return slists, and an slist may contain the values copied from another slist, rlist, or ilist. See policy.

ilist

Description: A list of integers

Type: ilist

Allowed input range: -99999999999,9999999999

Example:

    vars:

      "variable_id"

           ilist => { "10", "11", "12" };

Notes:

Integer lists are lists of strings that are expected to be treated as integers. The typing in CFEngine is dynamic, so the variable types are interchangeable, but when you declare a variable to be type ilist, CFEngine verifies that each value you assign to it looks like an integer (e.g., 3, -17, 16K).

Some functions return ilists, and an ilist may contain the values copied from another slist, rlist, or ilist. See policy

rlist

Description: A list of real numbers

Type: rlist

Allowed input range: -9.99999E100,9.99999E100

Example:

    vars:

      "varid" rlist => { "0.1", "0.2", "0.3" };

Notes:

Real lists are lists of strings that are expected to be used as real numbers. The typing in CFEngine is dynamic, so the variable types are interchangeable, but when you declare a variable to be type rlist, CFEngine verifies that each value you assign to it looks like a real number (e.g., 3, 3.1415, .17, 6.02e23, -9.21e-17).

Some functions return rlists, and an rlist may contain the values copied from another slist, rlist, or ilist. See policy

Attributes

policy

Description: The policy for (dis)allowing (re)definition of variables

Variables can either be allowed to change their value dynamically (be redefined) or they can be constant.

Type: (menu option)

Allowed input range:

    free
    overridable
    constant
    ifdefined

Default value:

policy = constant

Example:

    vars:

      "varid" string => "value...",
              policy => "constant";

Notes:

The policy constant indicates that the variable value may not be changed. The policies free and overridable are synonymous, and indicated that the variable's value may be changed.

The policy ifdefined applies only to lists and implies that unexpanded or undefined lists are dropped. The default behavior is otherwise to retain this value as an indicator of the failure to quench the variable reference, for example:

    "one" slist => { "1", "2", "3" };

    "list" slist => { "@(one)", @(two) },
          policy => "ifdefined";

This results in @(list) being the same as @(one), and the reference to @(two) disappears. This is useful for combining lists.