# cron parser
[](https://crates.io/crates/cron-parser)
[](https://github.com/nbari/cron-parser/actions/workflows/test.yml)
[](https://docs.rs/cron-parser)
Library for parsing cron expressions with timezone support.
Example:
use chrono::{TimeZone, Utc};
use chrono_tz::Europe::Lisbon;
use cron_parser::parse;
fn main() {
if let Ok(next) = parse("*/5 * * * *", &Utc::now()) {
println!("when: {}", next);
}
// passing a custom timestamp
if let Ok(next) = parse("0 0 29 2 *", &Utc.timestamp_opt(1893456000, 0).unwrap()) {
println!("next leap year: {}", next);
assert_eq!(next.timestamp(), 1961625600);
}
assert!(parse("2-3,9,*/15,1-8,11,9,4,5 * * * *", &Utc::now()).is_ok());
assert!(parse("* * * * */Fri", &Utc::now()).is_err());
// use custom timezone
assert!(parse("*/5 * * * *", &Utc::now().with_timezone(&Lisbon)).is_ok());
}
Cron table:
```
# ┌───────────────────── minute (0 - 59)
# │ ┌─────────────────── hour (0 - 23)
# │ │ ┌───────────────── dom (1 - 31) day of month
# │ │ │ ┌─────────────── month (1 - 12)
# │ │ │ │ ┌───────────── dow (0 - 6 or Sun - Sat) day of week (Sunday to Saturday)
# │ │ │ │ │
# │ │ │ │ │
# │ │ │ │ │
# * * * * * <command to execute>
```
| Minutes | Yes | 0–59 | \* , - / |
| Hours | Yes | 0–23 | \* , - / |
| Day of month | Yes | 1–31 | \* , - / |
| Month | Yes | 1–12 | \* , - / |
| Day of week | Yes | 0–6 or Sun-Sat | \* , - / |
> For the day of the week, when using a Weekday (Sun-Sat) the expression `*/Day` is not supported instead
> use the integer, reasons for this is that for example `*/Wed` = `*/3` translates
> to run every 3rd day of week, this means Sunday, Wednesday, Saturday.
* `*` any value
* `,` value list separator
* `-` range of values
* `/` step values
## start-end/step
Ranges with steps are supported, for example:
```
0 12-18/3 * * * # every 3 hours starting from 12 to 18
```
Or every 6 hours starting from 1:
```
0 1/6 * * *
```
## Examples
The library includes several example programs demonstrating different use cases:
### Parse Example
Interactive cron expression parser that shows next execution times:
```bash
cargo run --example parse -- "*/5 * * * *"
cargo run --example parse -- "0 9 * * 1-5" --count 10
cargo run --example parse -- "0 12-18/3 * * *" --count 10
```
### Timezone Example
Demonstrates how cron expressions work across different timezones:
```bash
cargo run --example timezone
```
### Patterns Example
Showcases common cron expression patterns:
```bash
cargo run --example patterns
```
See the [examples/](examples/) directory for the full source code.
## Dependencies
Depends on crate [chrono](https://crates.io/crates/chrono).
Example of `Cargo.toml`:
[dependencies]
chrono = "^0.4"
cron-parser = "*"
Getting the next 10 leap year iterations:
use chrono::{DateTime, Utc};
use cron_parser::parse;
fn main() {
let now = Utc::now();
let mut crons = Vec::<DateTime<Utc>>::new();
let mut next = parse("0 0 29 2 *", &now).unwrap();
for _ in 0..10 {
next = parse("0 0 29 2 *", &next).unwrap();
crons.push(next);
}
for x in crons {
println!("{} - {}", x, x.timestamp());
}
}
It will print something like:
2024-02-29 00:00:00 UTC - 1709164800
2028-02-29 00:00:00 UTC - 1835395200
2032-02-29 00:00:00 UTC - 1961625600
2036-02-29 00:00:00 UTC - 2087856000
2040-02-29 00:00:00 UTC - 2214086400
2044-02-29 00:00:00 UTC - 2340316800
2048-02-29 00:00:00 UTC - 2466547200
2052-02-29 00:00:00 UTC - 2592777600
2056-02-29 00:00:00 UTC - 2719008000
2060-02-29 00:00:00 UTC - 2845238400