$exist
Check whether the specified header or property variable exists.
Syntax:
$exist( name )
Parameters:
name – the name of the header or property variable
Returns:
true – if the specified header or variable exists.
false – otherwise
Version Since:
2.5
Where the function can be used:
- Preliminary rules
- Regular rules
Example:
$exist( “P-Called-Party-ID” ) = false
If P-Called-Party-ID header doesn’t exist.
$exist( “&my.val” ) = true
If the variable “my.val” exists.