DATECONV(1)

🦋 hey bestie, welcome to dateconv 🦋

ok so real talk: this is dateconv from section 1 of the manual — User Commands territory — shipped as part of dateutils. it's the little gremlin that takes a date/time and ✨transforms✨ it into another calendrical system. no cap, it's giving time-travel but make it command-line. 💅

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🌸 NAME 🌸

dateconv — Convert DATE/TIMEs between calendrical systems. (yes, that's the whole name, she's efficient like that 🎀)

⭐ SYNOPSIS ⭐

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

💖 DESCRIPTION 💖

Convert DATE/TIMEs between calendrical systems. and listen — if DATE/TIME is omitted, bestie, it just reads date/times from stdin. main character energy: she'll take input however you give it. 🫶

DATE/TIME can also be one of these specials, and they're lowkey 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 (get comfy, there's a bunch 👑):

🎀 OPTIONS 🎀

• -h, --help — Print help and exit. the "what do I do" button, we love her.
• -V, --version — Print version and exit. proof she exists.
• -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 yeah, -q is the "don't @ me" flag fr fr.
• -f, --format=STRING — Output format. This can either be a specifier string (similar to strftime()'s FMT) or the name of a calendar. pick your aesthetic 💅
• -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 one that sticks, wins — like a group project where whoever actually does the work gets the credit 😭
• -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. she'll fill in the blanks for you, bestie.
• -e, --backslash-escapes — Enable interpretation of backslash escapes in the output and input format specifier strings. because \n deserves to be a real newline.
• -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. literally sed but for dates, obsessed.
• -E, --empty-mode — Empty lines that cannot be parsed. if she can't read it, she blanks it. simple as. 💀
• --locale=LOCALE — Format results according to LOCALE, this would only affect month and weekday names. just the names, she's not doing 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. heads up: month/weekday names only — you still gotta spell out those input formats yourself.
• --from-zone=ZONE — Interpret dates on stdin or the command line as coming from the time zone ZONE. "this timestamp is from there, not here."
• -z, --zone=ZONE — Convert dates printed on stdout to time zone ZONE, default: UTC. and yes, default is UTC — she said standards, she said canon. 🌈

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✨ FORMAT SPECS ✨

Format specs in dateutils are similar to posix' strftime(). cute, right?

However, due to a broader range of supported calendars dateutils must employ different rules. so don't come at her with strftime expectations, she's built different. 🔥

📅 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 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 these two, for the calendars that don't play by unix rules:

• %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 moment 🥇:

• %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.

corporate era 💼:

• %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) — ok so ngl the manpage literally has a blank word right there, I'm not making this up 😭 she's shy. anyway: it's the 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. like, she said no. don't test her. 💀

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. (yes the @code{} is literally just chilling in there, she's a Texinfo baby, we don't judge 🫶)

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🍓 EXAMPLES 🍓

ok this is the part where it clicks, watch:

$ dconv 2012-03-01
2012-03-01
$

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

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

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

roman numerals in, cute little date out. ate. 👑

$ dconv 12:03:01
12:03:01
$

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

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

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

$ dconv --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
$

$ dconv --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
$

$ dconv --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
$

see? chronologically fluent. iykyk. 🌈

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👑 AUTHOR 👑

Written by Sebastian Freundt <freundt@fresse.org>. legend behavior, honestly. 🫶

🐛 REPORTING BUGS 🐛

Report bugs to: https://github.com/hroptatyr/dateutils/issues — be nice, be specific, include the receipts. 💅

💜 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. go read it, she's thorough. 📚

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and that's the whole page, bestie 🎀 this was dateutils version 0.4.11, dated January 2024 — mwah, go convert some dates, ily, bye 💖✨