DATESEQ(1)

💖 NAME 💖

okay so bestie, gather round, this is the manual for dateseq 💅 — that's DATESEQ(1) in the User Commands section, and yes she's serving. What does she do? Generate a sequence of date/times from FIRST to LAST, optionally in steps of — that's literally the official one-liner, no cap 🎀

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🦋 SYNOPSIS 🦋

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

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✨ DESCRIPTION ✨

So the whole vibe is this: you generate a sequence of date/times from FIRST to LAST, and if you want, you do it in steps of INCREMENT — and INCREMENT defaults to 1d 🫶

Now, plot twist, if LAST is omitted she just picks one for you:

• she defaults to now if FIRST is a date/time
• she defaults to today if FIRST is a date
• she defaults to time if FIRST is a time

And listen, the values of FIRST and LAST are always inclusive — like, no date/times before FIRST and no date/times after LAST will be printed. Periodt. Nothing sneaks past the gates 👑

Also, negative INCREMENTs must be given, i.e. if FIRST is newer than LAST. Like, you have to actually say it, she's not gonna guess 😭

Recognized *OPTION*s:

• -h, --help — Print help and exit ✨
• -V, --version — Print version and exit
• -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 basically, quiet mode = no drama on your terminal, but heads up you lose the warnings AND the fix-up messages, and it's the difference between quiet and that 2 exit code 💀)
• -f, --format=STRING — Output format. This can either be a specifier string (similar to strftime()'s FMT) or the name of a calendar 🌈
• -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 💜
• -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 🕐
• -e, --backslash-escapes — Enable interpretation of backslash escapes in the output and input format specifier strings 🎀
• --locale=LOCALE — Format results according to LOCALE, this would only affect month and weekday names
• --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
• -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 🙈
• --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 🔥
• --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 🧚

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🌸 FORMAT SPECS 🌸

Format specs in dateutils are similar to posix' strftime(). But plot twist — because she supports a broader range of calendars, dateutils has to employ different rules. It's giving very "we're not like other girls" but make it necessary 💅

🎀 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 original literally just says "The" and then a blank space here, I'm not making that up, that's exactly what's printed, iykyk 🫶
• %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. Like, that's just the rule, don't fight her on it 😤

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.

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🍓 SPECIFYING DURATIONS 🍓

Some tools ("dateadd", "dateseq") 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. She's not flexible on this one bestie, it's fixed 😭

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. Rip to that era 🪦

💖 EXAMPLES 💖

okay bestie, this is the part where it all comes together. real commands, real output, no cap. grab a snack 🍓, this is the whole vibe in action.

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✨ the classic: just two dates ✨

literally the most basic thing ever, one date to another, every single day in between. iconic.

$ dateseq 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
$

not the leap day showing up with main character energy 😌 happy 2012.

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✨ skipping the weekend like it's nothing ✨

--skip sat says bye to saturdays, and -f "%F %a" makes it print the date and the weekday name, so you can see exactly which day got ghosted. ngl this is my fave combo. 💅

$ dateseq 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
$

no sats in sight, lowkey therapeutic tbh 🦋

---

✨ same thing but backwards-aware ✨

--compute-from-last flips the math so the increment is counted off the last date instead of the first. and guess what — with a plain day count of 1 and --skip sat, the output is identical to the one above. sometimes you take a different road and arrive at the same slay. 😌

$ dateseq --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
$

---

✨ every 3 days, and we hate sat & fri ✨

now we're cooking. increment of 3, and --skip sat,fri clears out two whole days of the week. it's giving chaotic calendar. 🌈

$ dateseq 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
$

and now the exact same flags but counting from the last date instead of the first — totally different output, so watch out. 👀

$ dateseq --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?? different. bestie, --compute-from-last fr fr changes the whole game, periodt.

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✨ stepping every 4 days, no skipping at all ✨

just vibes, four at a time, starting from the first date:

$ dateseq 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
$

and from-last version, where the last date is guaranteed to land in the output (it's 2001-03-04 Sun, right at the bottom — she said I'm the finale) 👑

$ dateseq --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
$

---

✨ it's giving alternate increments ✨

--alt-inc 1d drops in an alternate increment of 1d for the days that would otherwise get skipped by the --skip rules. so instead of jumping over sat and fri entirely, it sneaks a little 1d hop in. sneaky. love her. 💅

$ dateseq --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 with --compute-from-last stacked on top of it? literally the same output. two routes, one destination, we love a consistent queen 🎀

$ dateseq --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
$

---

✨ duration increments: forward edition ✨

watch this — the increment 2d means "every two days" and the output hits the odd-numbered days. classic.

$ dateseq 2001-01-01 2d 2001-01-08
2001-01-01
2001-01-03
2001-01-05
2001-01-07
$

same command, <purple>--compute-from-last</purple>:

$ dateseq --compute-from-last 2001-01-01 2d 2001-01-08
2001-01-02
2001-01-04
2001-01-06
2001-01-08
$

flipped to even days and the final date actually shows up. balance 💖

---

✨ negative durations, going backwards ✨

-2d = walking backwards, two days at a time. first one starts at the head:

$ dateseq 2001-01-08 -2d 2001-01-01
2001-01-08
2001-01-06
2001-01-04
2001-01-02
$

and from-last, so 2001-01-01 gets the last word:

$ dateseq --compute-from-last 2001-01-08 -2d 2001-01-01
2001-01-07
2001-01-05
2001-01-03
2001-01-01
$

it's giving time travel but make it orderly 🕰️✨

---

✨ clock time, every 12 minutes ✨

not just dates bestie, times too. 12m = twelve minutes. ⏰

$ dateseq 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
$

from-last, and 11:20:00 closes the show:

$ dateseq --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
$

now backwards, negative increment, starting at the tail:

$ dateseq 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
$

and finally, negative increment + from-last, landing right on 10:00:00:

$ dateseq --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
$

that's the whole anthology, no notes. 😭💖

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👑 AUTHOR 👑

Written by Sebastian Freundt <freundt@fresse.org>

(yes, the icon who built all of this. we stan.)

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🐛 REPORTING BUGS 🐛

found something cursed? Report bugs to: https://github.com/hroptatyr/dateutils/issues

pls be nice and specific when you file it — the maintainers are doing the lord's work 🙏

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🦋 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.

iykyk — when in doubt, the info pages are always there for you like a ride-or-die bestie. 🌸

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and that's a wrap on the dateseq(1) page, bestie!! this edition was dateutils 0.4.11, dated November 2025, filed under DATESEQ(1). go forth and generate all the dates your heart desires — you got this, mwah 💜💅✨