# crontab

**Repository Path**: go-libs/crontab

## Basic Information

- **Project Name**: crontab
- **Description**: This lib provides a ticker manager like linux crontab
- **Primary Language**: Go
- **License**: Apache-2.0
- **Default Branch**: dev
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2024-07-10
- **Last Updated**: 2024-12-16

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# Crontab

A processor run in goroutine like linux crontab.

## Timed execution crontab

| Field name   | Mandatory? | Allowed values  | Allowed special characters |
|--------------|------------|-----------------|----------------------------|
| Seconds      | No         | 0-59            | * / , -                    |
| Minutes      | Yes        | 0-59            | * / , -                    |
| Hours        | Yes        | 0-23            | * / , -                    |
| Day of month | Yes        | 1-31            | * / , - L W                |
| Month        | Yes        | 1-12 or JAN-DEC | * / , -                    |
| Day of week  | Yes        | 0-6 or SUN-SAT  | * / , - L #                |
| Year         | No         | 1970–2099       | * / , -                    |

#### Asterisk ( * )
The asterisk indicates that the cron expression matches for all values of the field. E.g., using an asterisk in the 4th field (month) indicates every month.

#### Slash ( / )
Slashes describe increments of ranges. For example `3-59/15` in the minute field indicate the third minute of the hour and every 15 minutes thereafter. The form `*/...` is equivalent to the form "first-last/...", that is, an increment over the largest possible range of the field.

#### Comma ( , )
Commas are used to separate items of a list. For example, using `MON,WED,FRI` in the 5th field (day of week) means Mondays, Wednesdays and Fridays.

#### Hyphen ( - )
Hyphens define ranges. For example, 2000-2010 indicates every year between 2000 and 2010 AD, inclusive.

#### L
`L` stands for "last". When used in the day-of-week field, it allows you to specify constructs such as "the last Friday" (`5L`) of a given month. In the day-of-month field, it specifies the last day of the month.

#### W
The `W` character is allowed for the day-of-month field. This character is used to specify the business day (Monday-Friday) nearest the given day. As an example, if you were to specify `15W` as the value for the day-of-month field, the meaning is: "the nearest business day to the 15th of the month."

So, if the 15th is a Saturday, the trigger fires on Friday the 14th. If the 15th is a Sunday, the trigger fires on Monday the 16th. If the 15th is a Tuesday, then it fires on Tuesday the 15th. However if you specify `1W` as the value for day-of-month, and the 1st is a Saturday, the trigger fires on Monday the 3rd, as it does not 'jump' over the boundary of a month's days.

The `W` character can be specified only when the day-of-month is a single day, not a range or list of days.

The `W` character can also be combined with `L`, i.e. `LW` to mean "the last business day of the month."

#### Hash ( # )
`#` is allowed for the day-of-week field, and must be followed by a number between one and five. It allows you to specify constructs such as "the second Friday" of a given month.