DATECONV(1)

💖 DATECONV(1) — the dateutils glow-up 💖

okay bestie, listen. this is dateconv, a User Commands girlie from the dateutils fam, and she converts DATE/TIMEs between calendrical systems. no cap. that's the whole personality. let's go 🦋

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✨ NAME ✨

dateconv — Convert DATE/TIMEs between calendrical systems. 💅

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🎀 SYNOPSIS 🎀

dateconv [OPTION]...  [DATE/TIME]...

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🌸 DESCRIPTION 🌸

She converts DATE/TIMEs between calendrical systems, periodt. And if you just… don't give her a DATE/TIME? No worries! She reads date/times from stdin instead. main character energy tbh 🫶

DATE/TIME can also be one of these little specials, they're iconic:

• now — interpreted as the current (UTC) time stamp ⏰
• time — the time part of the current (UTC) time stamp
• today — the current date (according to UTC)
• tomo[rrow] — tomorrow's date (according to UTC) 🌅
• y[ester]day — yesterday's date (according to UTC) 😭

Recognized OPTIONs (yes, she has options, she's booked and busy):

• -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 if you want the receipts, don't pass this bestie)
• -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.
• -S, --sed-mode — Copy parts from the input before and after a matching date/time. Note that all occurrences of date/times within a line will be processed.
• -E, --empty-mode — Empty lines that cannot be parsed.
• --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.
• --from-zone=ZONE — Interpret dates on stdin or the command line as coming from the time zone ZONE. 🌍
• -z, --zone=ZONE — Convert dates printed on stdout to time zone ZONE, default: UTC.

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🧚 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. (she contains multitudes, okay?)

🗓️ 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)

and then the roman numeral girlies 👑

• %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

and the epoch / calendar-year specials:

• %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.

ordinal era 💅:

• %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.

and the business day besties:

• %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 second (range 00 to 60, 60 is for leap seconds)
• %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. 😭 she said no.

For conformity here is a list of calendar designators and their corresponding format string — she's an open book fr fr:

• 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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🔥 EXAMPLES 🔥

look at her go, she ate:

$ dateconv 2012-03-01
2012-03-01
$

$ dateconv -i "%d/%b/%y" 01/Mar/12
2012-03-01
$

$ dateconv -f "%d/%b/%y" 2012-03-01
01/Mar/12
$

$ dateconv -f "%d/%b/%y" -i "%OY %Om %Od" "MCMXCVIII IX XVII"
17/Sep/98
$

$ dateconv 12:03:01
12:03:01
$

$ dateconv -i "%I:%M:%S %p" "11:22:33 PM"
23:22:33
$

$ dateconv '2012-03-01 00:00:00'
2012-03-01T00:00:00
$

$ dateconv 2012-03-01T12:34:56
2012-03-01T12:34:56
$

$ dateconv --zone America/Chicago <<EOF
2012-03-01T07:05:06
2012-03-01T08:12:34
2012-03-11T01:05:06
2012-03-11T02:05:06
2012-03-11T07:05:06
2012-03-11T08:05:06
2012-03-11T17:05:06
EOF
2012-03-01T01:05:06
2012-03-01T02:12:34
2012-03-10T19:05:06
2012-03-10T20:05:06
2012-03-11T01:05:06
2012-03-11T03:05:06
2012-03-11T12:05:06
$

$ dateconv --from-zone America/Chicago <<EOF
2012-03-01T01:05:06
2012-03-01T02:12:34
2012-03-10T19:05:06
2012-03-10T20:05:06
2012-03-11T01:05:06
2012-03-11T03:05:06
2012-03-11T12:05:06
EOF
2012-03-01T07:05:06
2012-03-01T08:12:34
2012-03-11T01:05:06
2012-03-11T02:05:06
2012-03-11T07:05:06
2012-03-11T08:05:06
2012-03-11T17:05:06
$

$ dateconv --from-zone America/Chicago -z Europe/Berlin '2012-03-01 12:00' -i '%F %H:%M' -f '%F %T'
2012-03-01 19:00:00
$

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👑 AUTHOR 👑

Written by Sebastian Freundt <freundt@fresse.org> — we love a legend 💜

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🐛 REPORTING BUGS 🐛

Found a bug? bestie pls report it here, she wants to know:

https://github.com/hroptatyr/dateutils/issues

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👀 SEE ALSO 👀

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

info (dateutils)dateconv

should give you access to the complete manual. iykyk 🧚

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that's the whole page bestie, slay 💅 this was dateutils version 0.4.11, dated November 2025. go convert some dates, you got this 🫶✨