# Cron

A CRON expression is simply a string consisting of six fields that each define a specific unit of time. 

They are written in the following format:

```
{second} {minute} {hour} {day} {month} {day of the week}
```

---
## Values

The following values are allowed within each date/time unit placeholder.

| Field | Allowed Values | Description |
|---|---|---|
| {second} | 0-59 | Trigger every {second} second(s) |
| {minute} | 0-59 | Trigger every {minute} minute(s) | 
| {hour} | 0-23 | Trigger every {hour} hour(s) |
| {day} | 1-31 | Trigger every {day} day(s) of month |
| {month} | 1-12 | Trigger every {month} month(s) |
| {day of week} | 0-6 | MON-SUN Trigger on specific {day of week} |

---
## Special Characters

Additionally you can also use the following special characters to build more advanced expressions:

| Special Character | Description |
|---|---|
| `*` | Trigger on tick of every time unit |
| `,` | List separator |
|`–` | Specifies a range |
| `/` | Defines an increment |

---
## Examples

`0 * * * * *` - Executes every minute
`0 0 * * * *` - Executes every hour
`0 0 0 * * *` - Executes every day
`0 0 0 0 * *` - Executes every month
`0 0 0 1 1 *` - Executes on first day of Jan each year
`30 20 * * SAT` - Executes at 08:30pm every Saturday
`30 20 * * 6` - Executes at 08:30pm every Saturday
`0 */5 * * * *` - Executes every five minutes
`0 0 8-10/1 * * *` - Executes every hour between 8am and 10am