DATESEQ(1)

📦 version 0.4.11, in alpine 3.24, nixos 26.05, nixpkgs unstable, opensuse-leap 16.0

✨ NAME ✨

okay so this is dateseq(1), and the official name line is exactly: Generate a sequence of date/times from FIRST to LAST, optionally in steps of — yes, it trails off like that in the source, and we are respecting the lore. 💅

🌸 SYNOPSIS 🌸

dateseq [OPTION]...  FIRST [[INCREMENT] LAST]

💖 DESCRIPTION 💖

Generate a sequence of date/times from FIRST to LAST, optionally in steps of INCREMENT (which defaults to 1d). slay.

If LAST is omitted it defaults to now if FIRST is a date/time, or today if FIRST is a date, or time if FIRST is a time. iconic behavior, honestly.

The values of FIRST and LAST are always inclusive and no date/times before FIRST and no date/times after LAST will be printed. periodt.

Negative INCREMENTs must be given, i.e. if FIRST is newer than LAST. no cap, that’s the rule.

Recognized OPTIONs

  • -h, --help — Print help and exit. your little “what is this” button.
  • -V, --version — Print version and exit. the classic.
  • -q, --quiet — Suppress message about date/time and duration parser errors and fix-ups. The default is to print a warning or the fixed up value and return error code 2. so if you don’t pass this, expect the tea.
  • -f, --format=STRING — Output format. This can either be a specifier string (similar to strftime()'s FMT) or the name of a calendar. choose your fighter.
  • -i, --input-format=STRING... — Input format, can be used multiple times. Each date/time will be passed to the input format parsers in the order they are given, if a date/time can be read successfully with a given input format specifier string, that value will be used. first match wins, basically.
  • -b, --base=DT — For underspecified input use DT as a fallback to fill in missing fields. Also used for ambiguous format specifiers to position their range on the absolute time line. Must be a date/time in ISO8601 format. If omitted defaults to the current date/time. the safety net era.
  • -e, --backslash-escapes — Enable interpretation of backslash escapes in the output and input format specifier strings. backslash girlies rise.
  • --locale=LOCALE — Format results according to LOCALE, this would only affect month and weekday names. it’s giving localized month names, not a whole personality change.
  • --from-locale=LOCALE — Interpret dates on stdin or the command line as coming from the locale LOCALE, this would only affect month and weekday names as input formats have to be specified explicitly. yes, explicit input formats stay explicit.
  • -s, --skip=STRING... — Skip weekdays specified by STRING. STRING can be a single weekday (Mon, Tue, etc.), and to skip several days the --skip option can be used multiple times. STRING can also be a comma-separated list of weekday names, or ss to skip weekends (sat+sun) altogether. STRING can also contain date ranges like mo-we for monday to wednesday. very flexible, very demure.
  • --alt-inc=STRING — Alternative increment to use when a date is hit that is skipped as per --skip. This increment will be applied until a non-skipped date is reached. The special case 0 (default) deactivates alternative incrementing. A useful value could be 1d for increasing sequences and -1d for decreasing sequences, so if a skipped date is encountered the next non-skipped date after/before will be used. the skip-proof backup plan.
  • --compute-from-last — Compute a start value from LAST using INCREMENT. This option has an effect only when INCREMENT is not a divisor of the duration between FIRST and LAST. In such case, an alternative FIRST will be computed by consecutively subtracting INCREMENT from LAST until FIRST is hit or crossed. math girlie moment.

🗓️ FORMAT SPECS 🗓️

Format specs in dateutils are similar to posix' strftime(). However, due to a broader range of supported calendars dateutils must employ different rules. so yeah, the list is long and we are reading all of it.

📅 Date specs

  • %a — The abbreviated weekday name
  • %A — The full weekday name
  • %_a — The weekday name shortened to a single character (MTWRFAS)
  • %b — The abbreviated month name
  • %B — The full month name
  • %_b — The month name shortened to a single character (FGHJKMNQUVXZ)
  • %c — The count of the weekday within the month (range 00 to 05)
  • %C — The count of the weekday within the year (range 00 to 53)
  • %d — The day of the month, 2 digits (range 00 to 31)
  • %D — The day of the year, 3 digits (range 000 to 366)
  • %F — Equivalent to %Y-%m-%d (ymd's canonical format)
  • %g — ISO week date year without the century (range 00 to 99)
  • %G — ISO week date year including the century
  • %j — Equivalent to %D
  • %m — The month in the current calendar (range 00 to 12)
  • %Q — The quarter of the year (range Q1 to Q4)
  • %q — The number of the quarter (range 01 to 04)
  • %s — The number of seconds since the Epoch.
  • %u — The weekday as number (range 01 to 07, Sunday being 07)
  • %U — The week count, day of week is Sun (range 00 to 53)
  • %V — The ISO week count, day of week is Mon (range 01 to 53)
  • %w — The weekday as number (range 00 to 06, Sunday being 00)
  • %W — The week count, day of week is Mon (range 00 to 53)
  • %y — The year without a century (range 00 to 99)
  • %Y — The year including the century
  • %_y — The year shortened to a single digit
  • %Z — The zone offset in hours and minutes (HH:MM) with a preceding sign (+ for offsets east of UTC, - for offsets west of UTC)
  • %Od — The day as roman numerals
  • %Om — The month as roman numerals
  • %Oy — The two digit year as roman numerals
  • %OY — The year including the century as roman numerals
  • %rs — In time systems whose Epoch is different from the unix Epoch, this selects the number of seconds since then.
  • %rY — In calendars with years that don't coincide with the Gregorian years, this selects the calendar's year.
  • %dth — The day of the month as an ordinal number, 1st, 2nd, 3rd, etc.
  • %mth — The month of the year as an ordinal number, 1st, 2nd, 3rd, etc.
  • %db — The business day of the month (since last month's ultimo)
  • %dB — Number of business days until this month's ultimo

⏰ Time specs

  • %H — The hour of the day using a 24h clock, 2 digits (range 00 to 23)
  • %I — The hour of the day using a 12h clock, 2 digits (range 01 to 12)
  • %M — The minute (range 00 to 59)
  • %N — The nanoseconds (range 000000000 to 999999999)
  • %p — The string AM or PM, noon is PM and midnight is AM.
  • %P — Like %p but in lowercase
  • %S — “The (range 00 to 60, 60 is for leap seconds)” — yes, the source leaves the noun out here; the range and leap-second fact are the important bits, bestie.
  • %T — Equivalent to %H:%M:%S

✨ General specs

  • %n — A newline character
  • %t — A tab character
  • %% — A literal % character

🎀 Modifiers

  • %O — Modifier to turn decimal numbers into Roman numerals
  • %r — Modifier to turn units into real units
  • %0 — Modifier to turn on zero prefixes
  • %SPC — Modifier to turn on space prefixes
  • %- — Modifier to turn off prefixes altogether
  • th — Suffix, read and print ordinal numbers
  • b — Suffix, treat days as business days
⚠️ By design dates before 1601-01-01 are not supported.

For conformity here is a list of calendar designators and their corresponding format string:

  • ymd — %Y-%m-%d
  • ymcw — %Y-%m-%c-%w
  • ywd — %rY-W%V-%u
  • bizda — %Y-%m-%db
  • lilian — n/a
  • ldn — n/a
  • julian — n/a
  • jdn — n/a
  • matlab — n/a
  • mdn — n/a

These designators can be used as output format string, moreover, @code{lilian}/@code{ldn} and @code{julian}/@code{jdn} can also be used as input format string. and yes, those raw @code{...} bits are literally in the source — iykyk 💅

⏳ SPECIFYING DURATIONS ⏳

Some tools ("dadd", "dseq") need durations as their input. Durations are generally incompatible with input formats as specified by "-i|--input-format" and (at the moment) the input syntax is fixed. so don’t try to freestyle it too hard.

The general format is "+-Nunit" where "+" or "-" is the sign, "N" a number, and "unit" the unit as discussed below.

Units:

  • s — seconds
  • m — minutes
  • h — hours
  • rs — real-life seconds, as in including leap transitions
  • d — days
  • b — business days
  • mo — months
  • y — years

For historical reasons, we used to accept "m" in the context of date-only input as a qualifier for months. As of 0.4.4, this is no longer the case. the more you know 🌈

✨ EXAMPLES ✨

okay bestie, this is the part where it all clicks 💖 these are real, actual outputs — copy them, run them, live your truth. Watch how the same little date-range gets completely different answers depending on which flags you throw at it 👑

🗓️ the classic: just walk the days

$ dseq 2012-02-01 2012-03-01
2012-02-01
2012-02-02
2012-02-03
2012-02-04
2012-02-05
2012-02-06
2012-02-07
2012-02-08
2012-02-09
2012-02-10
2012-02-11
2012-02-12
2012-02-13
2012-02-14
2012-02-15
2012-02-16
2012-02-17
2012-02-18
2012-02-19
2012-02-20
2012-02-21
2012-02-22
2012-02-23
2012-02-24
2012-02-25
2012-02-26
2012-02-27
2012-02-28
2012-02-29
2012-03-01
$

no increment given? it just gives you every single day, one per line, no notes. and yeah — it sailed right through 2012-02-29 because 2012 was a leap year, she ate that 🦋

🚫 skipping saturdays like it's nothing

$ dseq 2001-02-03 2001-03-03 --skip sat -f "%F %a"
2001-02-04 Sun
2001-02-05 Mon
2001-02-06 Tue
2001-02-07 Wed
2001-02-08 Thu
2001-02-09 Fri
2001-02-11 Sun
2001-02-12 Mon
2001-02-13 Tue
2001-02-14 Wed
2001-02-15 Thu
2001-02-16 Fri
2001-02-18 Sun
2001-02-19 Mon
2001-02-20 Tue
2001-02-21 Wed
2001-02-22 Thu
2001-02-23 Fri
2001-02-25 Sun
2001-02-26 Mon
2001-02-27 Tue
2001-02-28 Wed
2001-03-01 Thu
2001-03-02 Fri
$

look at that — 2001-02-10, 2001-02-17, 2001-02-24 are gone, not a single Sat in sight 😌 and the -f "%F %a" is showing you the weekday so you can literally verify it yourself. trust but verify, bestie 💅

🪄 same thing, but counting backwards from the end

$ dseq --compute-from-last 2001-02-03 1 2001-03-03 --skip sat -f "%F %a"
2001-02-04 Sun
2001-02-05 Mon
2001-02-06 Tue
2001-02-07 Wed
2001-02-08 Thu
2001-02-09 Fri
2001-02-11 Sun
2001-02-12 Mon
2001-02-13 Tue
2001-02-14 Wed
2001-02-15 Thu
2001-02-16 Fri
2001-02-18 Sun
2001-02-19 Mon
2001-02-20 Tue
2001-02-21 Wed
2001-02-22 Thu
2001-02-23 Fri
2001-02-25 Sun
2001-02-26 Mon
2001-02-27 Tue
2001-02-28 Wed
2001-03-01 Thu
2001-03-02 Fri
$

same output as above — because with an increment of 1 and only saturdays skipped, forward and backward land in the exact same spot. cute coincidence, not a guarantee ✨

🔥 now THIS is where it gets spicy

$ dseq 2001-02-03 3 2001-03-03 --skip sat,fri -f "%F %a"
2001-02-06 Tue
2001-02-12 Mon
2001-02-15 Thu
2001-02-18 Sun
2001-02-21 Wed
2001-02-27 Tue
$
$ dseq --compute-from-last 2001-02-03 3 2001-03-03 --skip sat,fri -f "%F %a"
2001-02-04 Sun
2001-02-07 Wed
2001-02-13 Tue
2001-02-19 Mon
2001-02-22 Thu
2001-02-25 Sun
2001-02-28 Wed
$

see how these two are completely different?? 😭 same args, same skips, only --compute-from-last flipped — and the whole list shifts. that's the vibe check: with a step of 3 and two skipped days, direction genuinely matters. no cap.

🧚 plain stepping, no skips at all

$ dseq 2001-02-05 4 2001-03-04 -f "%F %a"
2001-02-05 Mon
2001-02-09 Fri
2001-02-13 Tue
2001-02-17 Sat
2001-02-21 Wed
2001-02-25 Sun
2001-03-01 Thu
$
$ dseq --compute-from-last 2001-02-05 4 2001-03-04 -f "%F %a"
2001-02-08 Thu
2001-02-12 Mon
2001-02-16 Fri
2001-02-20 Tue
2001-02-24 Sat
2001-02-28 Wed
2001-03-04 Sun
$

forward lands on the start date, backward lands on the end date. both valid, both slaying, pick your fighter 🌈

🌸 --alt-inc, the main character

$ dseq --alt-inc 1d 2001-02-03 3 2001-03-03 --skip sat,fri -f "%F %a"
2001-02-04 Sun
2001-02-07 Wed
2001-02-11 Sun
2001-02-14 Wed
2001-02-18 Sun
2001-02-21 Wed
2001-02-25 Sun
2001-02-28 Wed
$
$ dseq --compute-from-last --alt-inc 1d 2001-02-03 3 2001-03-03 --skip sat,fri -f "%F %a"
2001-02-04 Sun
2001-02-07 Wed
2001-02-11 Sun
2001-02-14 Wed
2001-02-18 Sun
2001-02-21 Wed
2001-02-25 Sun
2001-02-28 Wed
$

and here they converge again 😌 with --alt-inc 1d the alternative increment takes over the stepping, so the two directions give you the identical list. iconic behavior, honestly.

🎀 duration increments hitting different

$ dseq 2001-01-01 2d 2001-01-08
2001-01-01
2001-01-03
2001-01-05
2001-01-07
$
$ dseq --compute-from-last 2001-01-01 2d 2001-01-08
2001-01-02
2001-01-04
2001-01-06
2001-01-08
$

see it? forward starts at 2001-01-01; backward lands on 2001-01-08. every other day, both times. simple, clean, obsessed 🫶

🙈 negative increments, because why not

$ dseq 2001-01-08 -2d 2001-01-01
2001-01-08
2001-01-06
2001-01-04
2001-01-02
$
$ dseq --compute-from-last 2001-01-08 -2d 2001-01-01
2001-01-07
2001-01-05
2001-01-03
2001-01-01
$

walking backwards through time, but which end you anchor to still flips with --compute-from-last 💀

⏰ times, not just dates

$ dseq 10:00:00 12m 11:20:00
10:00:00
10:12:00
10:24:00
10:36:00
10:48:00
11:00:00
11:12:00
$
$ dseq --compute-from-last 10:00:00 12m 11:20:00
10:08:00
10:20:00
10:32:00
10:44:00
10:56:00
11:08:00
11:20:00
$

12m means twelve minutes here, and yes it works on bare clock times, not just full dates 👑

💜 and going backward in time

$ dseq 11:20:00 -12m 10:00:00
11:20:00
11:08:00
10:56:00
10:44:00
10:32:00
10:20:00
10:08:00
$
$ dseq --compute-from-last 11:20:00 -12m 10:00:00
11:12:00
11:00:00
10:48:00
10:36:00
10:24:00
10:12:00
10:00:00
$

negative increment = walk downhill on the clock. and --compute-from-last still does its little anchor flip. periodt. 💅

👑 AUTHOR

Written by Sebastian Freundt <freundt@fresse.org>

🐛 REPORTING BUGS

Report bugs to: https://github.com/hroptatyr/dateutils/issues

bestie if something's broken, tell the maintainers, not me — I'm just the messenger 💖

💖 SEE ALSO

The full documentation for dateseq is maintained as a Texinfo manual. If the info and dateseq programs are properly installed at your site, the command

info (dateutils)dateseq

should give you access to the complete manual.

okay that's the whole page, you're officially a dseq girlie now 🌸 this gem is from dateutils 0.4.11, dated January 2024 — go forth and generate dates, bestie, and remember: when in doubt, --compute-from-last changes everything 🦋✨

📦 where this page comes from