healthchecks/templates/front/docs_cron.html

{% extends "front/base_docs.html" %}
{% load hc_extras %}

{% block title %}Cron Syntax Cheatsheet - {% site_name %}{% endblock %}

{% block description %}
    <meta name="description" content="Visual examples of main Cron syntax features: numeric values, commas, ranges, ranges with step, day and month names.">
{% endblock %}

{% block keywords %}
    <meta name="keywords" content="cron syntax, crontab syntax, cron howto, cron tutorial, cron jobs, cron job example, monitor cron jobs">
{% endblock %}

{% block docs_content %}

<h2>Cron Syntax Cheatsheet</h2>

<p>
    {% site_name %} understands most of the traditional cron syntax features.
    Under the hood, it uses the
    <a href="https://github.com/taichino/croniter">croniter package</a>
    to parse and interpret cron expressions. Below is a showcase of
    supported syntax features.
</p>
<p>
    <strong>Pro-tip!</strong>
    On Unix-like operating systems, you can also easily access cron syntax
    documentation by typing <code>man 5 crontab</code> in shell.
</p>
<br />

<div id="cron-examples">

    <div class="panel panel-default">
        <div class="panel-heading">
            <h3 class="panel-title">Basics</h3>
        </div>
        <div class="panel-body">
            <p>A cron expression has five fields, separated by spaces.
            Asterisk is a wild card character and means "any value".
            </p>

            <div class="desc">"Run every minute"</div>

            <table class="cron-example">
                <tr>
                    <th><div>* <span></span></div></th>
                    <th><div>*</div></th>
                    <th><div>*</div></th>
                    <th><div>*</div></th>
                    <th><div>*</div></th>
                </tr>
                <tr>
                    <td rowspan="5">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="4">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="3">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="2">
                        <div class="guide"></div>
                    </td>
                    <td>
                        <div class="guide"></div>
                    </td>
                    <td>Day of week, 0 - 7, 0 or 7 is Sun</td>
                </tr>
                <tr>
                    <td colspan="2">
                        Month, 1 - 12
                    </td>
                </tr>
                <tr>
                    <td colspan="3">
                        Day of month, 1 - 31
                    </td>
                </tr>
                <tr>
                    <td colspan="4">
                        Hour of day, 0 - 23
                    </td>
                </tr>
                <tr>
                    <td colspan="5">
                        Minute, 0 - 59
                    </td>
                </tr>
            </table>
        </div>
    </div>

    <div class="panel panel-default">
        <div class="panel-heading">
            <h3 class="panel-title">Numeric values</h3>
        </div>
        <div class="panel-body">
            <p>Use numeric values instead of asterisks to match specific
               minutes, hours, days and months.
            </p>

            <div class="desc">"Run at 6PM on Fridays"</div>

            <table class="cron-example">
                <tr>
                    <th><div>0 <span></span></div></th>
                    <th><div>18</div></th>
                    <th><div>*</div></th>
                    <th><div>*</div></th>
                    <th><div>5</div></th>
                </tr>
                <tr>
                    <td rowspan="5">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="4">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="3">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="2">
                        <div class="guide"></div>
                    </td>
                    <td>
                        <div class="guide"></div>
                    </td>
                    <td>Run only on Fridays</td>
                </tr>
                <tr>
                    <td colspan="2" class="minor">
                        Run every month of the year
                    </td>
                </tr>
                <tr>
                    <td colspan="3" class="minor">
                        Run every day of the month
                    </td>
                </tr>
                <tr>
                    <td colspan="4">
                        Run at 6PM
                    </td>
                </tr>
                <tr>
                    <td colspan="5">
                        Run at the start of the hour
                    </td>
                </tr>
            </table>
        </div>
    </div>

    <div class="panel panel-default">
        <div class="panel-heading">
            <h3 class="panel-title">Commas</h3>
        </div>
        <div class="panel-body">
            <p>Use <code>{v1},{v2},...,{vn}</code> to list multiple values.</p>

            <div class="desc">"Run at 9AM, 12PM and 6PM every day"</div>

            <table class="cron-example">
                <tr>
                    <th><div>0 <span></span></div></th>
                    <th><div>9,12,18</div></th>
                    <th><div>*</div></th>
                    <th><div>*</div></th>
                    <th><div>*</div></th>
                </tr>
                <tr>
                    <td rowspan="5">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="4">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="3">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="2">
                        <div class="guide"></div>
                    </td>
                    <td>
                        <div class="guide"></div>
                    </td>
                    <td class="minor">Run on every weekday</td>
                </tr>
                <tr>
                    <td colspan="2" class="minor">
                        Run every month of the year
                    </td>
                </tr>
                <tr>
                    <td colspan="3" class="minor">
                        Run every day of the month
                    </td>
                </tr>
                <tr>
                    <td colspan="4">
                        Run at 9AM, 12PM and 6PM
                    </td>
                </tr>
                <tr>
                    <td colspan="5">
                        Run at the start of the hour
                    </td>
                </tr>
            </table>
        </div>
    </div>

    <div class="panel panel-default">
        <div class="panel-heading">
            <h3 class="panel-title">Ranges of values</h3>
        </div>
        <div class="panel-body">
            <p>Use <code>{start}-{end}</code> to define a range of matching values.</p>

            <div class="desc">"Run every minute on workdays"</div>

            <table class="cron-example">
                <tr>
                    <th><div>* <span></span></div></th>
                    <th><div>*</div></th>
                    <th><div>*</div></th>
                    <th><div>*</div></th>
                    <th><div>1-5</div></th>
                </tr>
                <tr>
                    <td rowspan="5">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="4">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="3">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="2">
                        <div class="guide"></div>
                    </td>
                    <td>
                        <div class="guide"></div>
                    </td>
                    <td>Run on Monday to Friday</td>
                </tr>
                <tr>
                    <td colspan="2" class="minor">
                        Run every month of the year
                    </td>
                </tr>
                <tr>
                    <td colspan="3" class="minor">
                        Run every day of the month
                    </td>
                </tr>
                <tr>
                    <td colspan="4" class="minor">
                        Run every hour of the day
                    </td>
                </tr>
                <tr>
                    <td colspan="5" class="minor">
                        Run every minute of the hour
                    </td>
                </tr>
            </table>
        </div>
    </div>

    <div class="panel panel-default">
        <div class="panel-heading">
            <h3 class="panel-title">Ranges with a step</h3>
        </div>
        <div class="panel-body">
            <p>Use <code>{start}-{end}/{step}</code> or <code>*/{step}</code>
               to define a range with a step.</p>

            <div class="desc">"Run every quarter of an hour"</div>

            <table class="cron-example">
                <tr>
                    <th><div>*/15 <span></span></div></th>
                    <th><div>*</div></th>
                    <th><div>*</div></th>
                    <th><div>*</div></th>
                    <th><div>*</div></th>
                </tr>
                <tr>
                    <td rowspan="5">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="4">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="3">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="2">
                        <div class="guide"></div>
                    </td>
                    <td>
                        <div class="guide"></div>
                    </td>
                    <td class="minor">Run on every weekday</td>
                </tr>
                <tr>
                    <td colspan="2" class="minor">
                        Run every month of the year
                    </td>
                </tr>
                <tr>
                    <td colspan="3" class="minor">
                        Run every day of the month
                    </td>
                </tr>
                <tr>
                    <td colspan="4" class="minor">
                        Run every hour of the day
                    </td>
                </tr>
                <tr>
                    <td colspan="5">
                        Run every 15 minutes
                    </td>
                </tr>
            </table>
        </div>
    </div>

    <div class="panel panel-default">
        <div class="panel-heading">
            <h3 class="panel-title">Combine numeric values and ranges in lists</h3>
        </div>
        <div class="panel-body">
            <p>In the comma-separated lists you can combine not only
            numeric values but also ranges.</p>

            <div class="desc">"Run every round hour outside office hours"</div>

            <table class="cron-example">
                <tr>
                    <th><div>0 <span></span></div></th>
                    <th><div>18-23,0-8</div></th>
                    <th><div>*</div></th>
                    <th><div>*</div></th>
                    <th><div>*</div></th>
                </tr>
                <tr>
                    <td rowspan="5">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="4">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="3">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="2">
                        <div class="guide"></div>
                    </td>
                    <td>
                        <div class="guide"></div>
                    </td>
                    <td class="minor">Run on every weekday</td>
                </tr>
                <tr>
                    <td colspan="2" class="minor">
                        Run every month of the year
                    </td>
                </tr>
                <tr>
                    <td colspan="3" class="minor">
                        Run every day of the month
                    </td>
                </tr>
                <tr>
                    <td colspan="4">
                        Run at 6PM, 7PM, 8PM, ..., 7AM, 8AM
                    </td>
                </tr>
                <tr>
                    <td colspan="5">
                        Run at the start of the hour
                    </td>
                </tr>
            </table>
        </div>
    </div>

    <div class="panel panel-default">
        <div class="panel-heading">
            <h3 class="panel-title">Abbreviated day and month names</h3>
        </div>
        <div class="panel-body">
            <p><code>JAN-DEC</code> can be used in the month field
                and
                <code>MON-SUN</code> in the weekday field.
            </p>

            <div class="desc">"Run every round hour on April 1st"</div>

            <table class="cron-example">
                <tr>
                    <th><div>0 <span></span></div></th>
                    <th><div>*</div></th>
                    <th><div>1</div></th>
                    <th><div>APR</div></th>
                    <th><div>*</div></th>
                </tr>
                <tr>
                    <td rowspan="5">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="4">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="3">
                        <div class="guide"></div>
                    </td>
                    <td rowspan="2">
                        <div class="guide"></div>
                    </td>
                    <td>
                        <div class="guide"></div>
                    </td>
                    <td class="minor">Run on every weekday</td>
                </tr>
                <tr>
                    <td colspan="2">
                        Run in April
                    </td>
                </tr>
                <tr>
                    <td colspan="3">
                        Run on the first day of the month
                    </td>
                </tr>
                <tr>
                    <td colspan="4" class="minor">
                        Run every hour of the day
                    </td>
                </tr>
                <tr>
                    <td colspan="5">
                        Run at the start of the hour
                    </td>
                </tr>
            </table>
        </div>
    </div>

    <div class="panel panel-default">
        <div class="panel-heading">
            <h3 class="panel-title">Timezones</h3>
        </div>
        <div class="panel-body">
            <p>
                Cron daemon uses server's <strong>local time</strong>.
                If your server's timezone is other than UTC, make sure
                to set a matching timezone for your check
                on {% site_name %} as well.
            </p>

            <p>On Ubuntu systems you can check the server's timezone
            with:</p>
            <pre>cat /etc/timezone</pre>
        </div>
    </div>



</div> <!-- cron examples -->

{% endblock %}