--- title: Template Variable Evaluation description: >- Modify template variable output in monitor notifications using mathematical operations, functions, and string manipulation with eval syntax. breadcrumbs: Docs > Monitors > Monitor Guides > Template Variable Evaluation --- # Template Variable Evaluation In monitor notification messages, you can modify the output of template variables using the `eval` syntax, which enables several different mathematical operations and functions on template variables with a numerical or string value. ## Operators{% #operators %} Evaluation operators allow you to perform basic arithmetic operations on a numerical template variable. The syntax uses the following format. **Note**: The expressions must be wrapped in quotation marks (`"`). ```text {{eval "TEMPLATE_VARIABLE_NAME+1-2*3/4"}} ``` The following operators are supported: | Operator | Description | | -------- | -------------- | | + | Addition | | - | Subtraction | | \* | Multiplication | | / | Division | | ^ | Exponentiation | | % | Modulo | ### Example{% #example %} The `{{last_triggered_at_epoch}}` template variable returns the UTC time when a monitor last triggered in milliseconds epoch format. ### Scope links to specific times{% #scope-links-to-specific-times %} Evaluation operators can be used to subtract 15 minutes (15 * 60 * 1000 milliseconds) with the following: ``` {{eval "last_triggered_at_epoch-15*60*1000"}} ``` This is useful for creating time-scoped links in your monitor notification message to other pages in Datadog or other workflow tools. For instance, use the evaluation operators on `{{last_triggered_at_epoch}}` to create a time-scoped link to the [Datadog Log Explorer](https://docs.datadoghq.com/logs/explorer.md): ``` https://app.datadoghq.com/logs?from_ts={{eval "last_triggered_at_epoch-15*60*1000"}}&to_ts={{last_triggered_at_epoch}}&live=false ``` ### Routing notifications to different teams based on time of day{% #routing-notifications-to-different-teams-based-on-time-of-day %} You can combine a modulo `%` evaluation of the `last_triggered_at_epoch` variable with `{{#is_exact_match}}{{/is_exact_match}}` to customize the routing of notifications based on time of day (UTC): ``` {{#is_exact_match (eval "int(last_triggered_at_epoch / 3600000 % 24)") "8" "9" "10" "11" "12" "13"}} Handle that should receive notification if time is between 8AM and 2PM UTC {{/is_exact_match}} ``` **Note:** If you need to evaluate your monitor on a schedule, see [Custom Schedules](https://docs.datadoghq.com/monitors/guide/custom_schedules.md) instead. ## Functions{% #functions %} The value of a template variable can be used as the input for evaluation functions to change the formatting of the template variable or perform a mathematical operation on the value (if applicable). The syntax uses the following format. **Note**: The expressions must be wrapped in quotation marks (`"`). ```text {{eval "function(TEMPLATE_VARIABLE_NAME)"}} ``` {% tab title="Numeric variable" %} The following functions change how the value of a numerical template variable is formatted: | Function | Description | | ------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------- | | humanize_bytes(var) | Returns a human readable formatting of var bytes | | humanize_bits(var) | Returns a human readable formatting of var bits | | abs(var) | Returns the absolute value of var | | int(var) | Returns var as a floored integer; that is, the numbers to the left of the decimal point. For example: if var = 12.345, then `int(var)` returns 12. | | float(var) | Returns var as a float | | trunc(var) | Returns var as an integer, an alias of the int function | | dec(var) | Returns the numbers to the right of the decimal point. For example: if var = 12.345, then `dec(var)` returns 0.345. | The following functions use the value of a numerical template variable as the input to a mathematical function: | Function | Description | | ----------------- | ------------------------------------------------------------------------------------------------------------------------------ | | round(var) | Returns var rounded to the nearest integer | | round(var, n) | Returns var rounded to a specified number of digits (n).For example: round(12.376, 2) = 12.38 | | ceil(var) | Returns the ceiling of var (the smallest integer that is greater than or equal to var) | | floor(var) | Returns the floor of var (the largest integer that is less than or equal to var) | | sgn(var) | Returns the value of the sign function evaluated at var:sgn(var) = 1 if var > 0sgn(var) = 0 if var = 0sgn(var) = -1 if var < 0 | | to_bool(var) | Returns true if var = 1Returns false if var = 0 | | exp(var) | Returns e (the base of the natural logarithm) raised to the power of var | | log10(var) | Returns the base-10 logarithm of var | | sin(var) | Returns the sine of var radians | | sinh(var) | Returns the hyperbolic sine of var | | asin(var) | Returns the arc sine of var, in radians | | asinh(var) | Returns the inverse hyperbolic sine of var | | cos(var) | Returns the cosine of var radians | | cosh(var) | Returns the hyperbolic cosine of var | | acos(var) | Returns the arc cosine of var, in radians | | acosh(var) | Returns the inverse hyperbolic cosine of var | | tan(var) | Returns the tangent of var radians | | tanh(var) | Returns the hyperbolic tangent of var | | atan(var) | Returns the arc tangent of var, in radians | | atan2(var1, var2) | Returns atan(var1 / var2), in radians | | atanh(var) | Returns the inverse hyperbolic tangent of var | ### Examples{% #examples %} If the decimal places of the `{{value}}` template variable are unnecessary for your particular use case, use the int function to evaluate `{{value}}` as an integer to improve readability and remove the decimals: ``` {{eval "int(value)"}} ``` If `{{value}}` is evaluating to a large number of bytes or bits, use the `humanize_bytes` or `humanize_bits` function to convert the number to a different higher order memory unit like GB or MB to improve readability: ``` {{eval "humanize_bytes(value)"}} {{eval "humanize_bits(value)"}} ``` {% /tab %} {% tab title="String variable" %} The following functions can be used to perform certain operations on strings variables: | Function | Description | | -------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | upper(var) | Returns a string converted to uppercase letters | | lower(var) | Returns a string converted to lowercase letters | | substring(var, start, end) | Extracts characters from a string, between two specified indexes (start, end). The third parameter is optional.For example: substring("host:D", 5) = "D" | | strip(var, characters) | Remove the leading and trailing characters. When the second parameter is null, it removes spaces at the beginning and at the end of the string. For example:strip(" host:E ") = "host:E"strip("abchost:Eabc", "abc") = "host:E" | {% /tab %}