chrono systemd.time

The library parses timestamps following the systemd.time specifications into chrono types.

Timestamp Format

The supported timestamp formats are any defined by the systemd.time specifications, with a few exceptions:

• time units must accompany all time span values.
• time zone suffixes are not supported.
• weekday prefixes are not supported.

The format of a timestamp may be either a time, a time span, or a combination of a time +/- a time span.

• When only a time is given, the parsed time is returned.
• When only a time span is given, the time span is added or subtracted from the current time (now).
• When a combination of a time and a time span is given, the time span is added or subtracted from the parsed time.

Examples of parsing valid timestamps, assuming now is 2018-06-21 01:02:03:

    parse_timestamp_tz("2018-08-20 09:11:12.123", Utc) == "2018-08-20T09:11:12.000123Z"
    parse_timestamp_tz("2018-08-20 09:11:12", Utc) == "2018-08-20T09:11:12Z"
    parse_timestamp_tz("18-08-20 09:11:12 +2m", Utc) == "2018-08-20T09:13:12Z"
    parse_timestamp_tz("2018-08-20 + 1h2m3s", Utc) == "2018-08-20T01:02:03Z"
    parse_timestamp_tz("18-08-20 - 1h 2m 3s", Utc) == "2018-08-19T22:57:57Z"
    parse_timestamp_tz("09:11:12 -1day", Utc) == "2018-06-20T09:11:12Z"
    parse_timestamp_tz("09:11:12.123", Utc) == "2018-06-21T09:11:12.000123Z"
    parse_timestamp_tz("11:12", Utc) == "2018-06-21T11:12:00Z"
    parse_timestamp_tz("now", Utc) == "2018-06-21T01:02:03.203918151Z"
    parse_timestamp_tz("today", Utc) == "2018-06-21T00:00:00Z"
    parse_timestamp_tz("yesterday -2days", Utc) == "2018-06-18T00:00:00Z"
    parse_timestamp_tz("tomorrow +1week", Utc) == "2018-06-29T00:00:00Z"

    parse_timestamp_tz("epoch +1529578800s", Utc) == "2018-06-21T11:00:00Z"
    parse_timestamp_tz("@1529578800s", Utc) == "2018-06-21T11:00:00Z"
    parse_timestamp_tz("now +4h50m", Utc) == "2018-06-21T05:52:03.203918151Z"
    parse_timestamp_tz("4h50m left", Utc) == "2018-06-21T05:52:03.203918151Z"
    parse_timestamp_tz("+4h50m", Utc) == "2018-06-21T05:52:03.203918151Z"
    parse_timestamp_tz("now -3s", Utc) == "2018-06-21T01:02:00.203918151Z"
    parse_timestamp_tz("3s ago", Utc) == "2018-06-21T01:02:00.203918151Z"
    parse_timestamp_tz("-3s", Utc) == "2018-06-21T01:02:00.203918151Z"

Time

The syntax of a time consists of a set of keywords and strftime formats:

• "now", "epoch"
• "today", "yesterday", "tomorrow"
• "%y-%m-%d %H:%M:%S", "%Y-%m-%d %H:%M:%S"
• "%y-%m-%d %H:%M", "%Y-%m-%d %H:%M"
• "%y-%m-%d", "%Y-%m-%d"
• "%H:%M:%S"
• "%H:%M"

Strftime timestamps with a seconds component may also include a microsecond component, separated by a '.'.

• When the date is omitted, today is assumed.
• When the time is omitted, 00:00:00 is assumed.

Examples of valid times (assuming now is 2018-06-21 01:02:03):

    "2018-08-20 09:11:12.123" == "2018-08-20T09:11:12.000123"
        "2018-08-20 09:11:12" == "2018-08-20T09:11:12"
          "18-08-20 09:11:12" == "2018-08-20T09:11:12"
                 "2018-08-20" == "2018-08-20T00:00:00"
                   "18-08-20" == "2018-08-20T00:00:00"
                   "09:11:12" == "2018-06-21T09:11:12"
               "09:11:12.123" == "2018-06-21T09:11:12.000123"
                      "11:12" == "2018-06-21T11:12:00"
                        "now" == "2018-06-21T01:02:03.203918151"
                      "epoch" == "1970-01-01T00:00:00"
                      "today" == "2018-06-21T00:00:00"
                  "yesterday" == "2018-06-20T00:00:00"
                   "tomorrow" == "2018-06-22T00:00:00"

Time span

A time span is made up of a combination of time units, with the following time units understood:

• "usec", "us", "µs"
• "msec", "ms"
• "seconds", "second", "sec", "s"
• "minutes", "minute", "min", "m"
• "hours", "hour", "hr", "h"
• "days", "day", "d"
• "weeks", "week", "w"
• "months", "month", "M" (defined as 30.44 days)
• "years", "year", "y" (defined as 365.25 days)

All components of a time span are added together.

Examples of valid time spans:

          "3hours" == Duration::hours(3)
           "2d 5h" == Duration::days(2) + Duration::hours(5)
    "1y 10 months" == Duration::years(1) + Duration::months(10)
          "30m22s" == Duration::minutes(30) + Duration::seconds(22)
       "10m 2s 5m" == Duration::minutes(15) + Duration::seconds(2)
        "10d 2 5m" == Duration::days(10) + Duration::minutes(25)