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Test the existence of a value.


Returns 1 if exists, 0 otherwise.


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Import Version

This documentation was imported from Asterisk Version GIT-16-b8bf57dc38

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1 Comment

  1. Note that it says "test the existence of a value", not variable as I first had thought. I had expected EXISTS in the following code to return 1 because the variable ${foo} does exist as an empty variable (DumpChan confirms that it exists):

     same => n,Set(foo=)
    same => n,DumpChan()
    same => n,NoOp(EXISTS(foo): ${EXISTS(${foo})})

    But it returns 0 as ${foo} expands to an empty value. As far as I can tell, it is impossible in Asterisk to discern between an undefined variable and a defined but empty variable, because both seem to expand to an empty value.