What do the 5 fields in a standard Linux cron expression represent?

From left to right: 1. Minute (0–59), 2. Hour (0–23), 3. Day of Month (1–31), 4. Month (1–12 or JAN–DEC), 5. Day of Week (0–6 or SUN–SAT, where 0 and 7 = Sunday).

What does the forward slash '/' mean in a cron expression?

The forward slash specifies step values. For example, `*/15 * * * *` in the minute field means 'every 15 minutes', and `0 */2 * * *` means 'every 2 hours'.

How does standard Unix Cron contrast with Quartz Cron?

Unix Cron uses 5 fields (Minute to Day-of-Week). Quartz Cron uses 6 or 7 fields by adding a leading Seconds field (0–59) and an optional trailing Year field.

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Cron Expression Generator & Schedule Studio

Build and translate complex crontab scheduling expressions instantly. Visual frequency dials, time configuration, custom day & month multiple-selection list dropdowns—100% private in-browser client sandbox.

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1. Select Frequency

Execute Every (Periodicity Interval)

Minute

Specifies the numeric interval for execution (e.g. running every 2 hours or every 5 minutes).

2. Select Hour & Minute (Execution Time)

Disabled. Time select is not applicable when executing at a minute or hour frequency.

3. Select Days of the Month

Choose one or more specific calendar dates (1 to 31) for execution.

4. Select Months

Pick specific months of the year for executing scheduled tasks.

Generated Output

crontab format

* * * * *

min*

hour*

day*

month*

w-day*

Standard Crontab Reference Presets

Scheduler Frequency	Expression Code	Clipboard Copy
Crontab every minute	`* * * * *`
Crontab every 5 minutes	`/5 * * *`
Cron every 10 minutes	`/10 * * *`
Cron every 15 minutes	`/15 * * *`
Crontab every 30 minutes (crontab every 1/2 hour)	`/30 * * *`
Crontab every 60 minutes (crontab every hour)	`0 * * * *`
Cron every 2 hours	`0 /2 * *`
Cron every 4 hours	`0 /4 * *`
Cron every day / cron daily	`0 0 * * *`
Crontab Daily at 2:30 am	`30 2 * * *`
Crontab every 1 week	`0 0 * * 0`
Crontab every week on Wed	`0 0 * * 3`
Crontab every 1 month	`0 0 1 * *`
Crontab every month at 6:30 pm on 2nd	`30 18 2 * *`
Crontab every 6 months	`0 0 1 /6 `
Crontab every Sunday	`0 0 * * 0`
Crontab every weekend at 5:30 pm	`30 17 * * 0,6`
Crontab every Wednesday at 4:30 am	`30 4 * * 3`
Crontab every 1st of the month	`0 0 1 * *`
Crontab every 5th of the month	`0 0 5 * *`
Crontab every 3 months (Every quarter) on a weekend	`0 0 1 /3 `
Crontab every 1 year	`0 0 1 1 *`
Cron every sec	`Not possible to set in the expression. It starts with 1 minute`

What is a Crontab schedule?

A crontab (cron table) is a text configuration file used by Unix-like operating systems to automate the execution of background system tasks at specified date and time intervals. A standard cron pattern consists of five fields separated by spaces, representing minute, hour, day of the month, month, and day of the week.

Understanding Cron Operators

Cron parameters support a wide range of operators: asterisk (*) triggers every interval, comma (,) lists multiple target values, hyphen (-) defines numeric ranges, and slash (/) handles step intervals (e.g. */15 represents executing once every 15 minutes).

⏱️ Cron Syntax Architecture: The 5-Field UNIX Crontab Standard

Originating in UNIX Version 7, the cron time-based job scheduler allows operating systems and backend microservices to execute maintenance commands, backups, and data synchronization scripts at recurring intervals.

Field #	Field Name	Allowed Values	Special Characters
1	Minute	0 – 59	`* , - /`
2	Hour	0 – 23 (24-hour clock)	`* , - /`
3	Day of Month	1 – 31	`* , - / ? L W`
4	Month	1 – 12 (or JAN – DEC)	`* , - /`
5	Day of Week	0 – 6 (0 = Sunday, or SUN – SAT)	`* , - / ? L #`

⚡ Linux Cron (5 Fields) vs. Quartz / Spring Schedulers (6 Fields)

Standard Linux and macOS crontab files use 5 positional fields with minute-level precision. In contrast, enterprise Java frameworks (such as Quartz or Spring @Scheduled) and AWS CloudWatch Events prepend a 6th field for Seconds (0–59) and occasionally append a 7th field for Year. Always verify whether your target framework expects a 5-field or 6-field format.

❓ Frequently Asked Questions — Cron Expression Editor

What does */15 mean in the minute field?

The slash (/) operator denotes a step interval. */15 in the first column specifies execution every 15 minutes starting from minute 0 (i.e. at :00, :15, :30, and :45 of every hour).

How do I run a job only on business days (Monday to Friday)?

Set the 5th field (Day of Week) to 1-5 or MON-FRI. For example, 0 9 * * 1-5 runs every weekday at 9:00 AM.

How do I edit my crontab on Linux or macOS?

Open your terminal and run crontab -e to edit your scheduled jobs, or run crontab -l to list your currently active cron schedule.

What timezone does cron use?

UNIX cron runs by default in the server's local operating system timezone (often UTC on cloud servers). Verify your server timezone by running date in the shell before scheduling time-critical jobs.