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nifty command line date and time utilities; fast date calculations and conversion in the shell
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* bug/39:
  PEBKAC, use #else to provide hand-crafted htooe64()
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README.md

Dateutils

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Dateutils are a bunch of tools that revolve around fiddling with dates and times on the command line with a strong focus on use cases that arise when dealing with large amounts of financial data.

Dateutils are hosted primarily on github:

Below is a short list of examples that demonstrate what dateutils can do, for full specs refer to the info and man pages. For installation instructions refer to the INSTALL file.

Dateutils commands are prefixed with a d but otherwise resemble known unix commands for reasons of intuition. The only exception being strptime which is analogous to the libc function of the same name.

  • strptime Command line version of the C function
  • dateadd Add durations to dates or times
  • dateconv Convert dates or times between calendars
  • datediff Compute durations between dates or times
  • dategrep Grep dates or times in input streams
  • dateround Round dates or times to "fuller" values
  • dateseq Generate sequences of dates or times
  • datetest Compare dates or times
  • datezone Convert date/times to timezones in bulk

Examples

I love everything to be explained by example to get a first impression. So here it comes.

dateseq

A tool mimicking seq(1) but whose inputs are from the domain of dates rather than integers. Typically scripts use something like

$ for i in $(seq 0 9); do
    date -d "2010-01-01 +${i} days" "+%F"
  done

which now can be shortened to

$ dateseq 2010-01-01 2010-01-10

with the additional benefit that the end date can be given directly instead of being computed from the start date and an interval in days. Also, it provides date specific features that would be a PITA to implement using the above seq(1)/date(1) approach, like skipping certain weekdays:

$ dateseq 2010-01-01 2010-01-10 --skip sat,sun
=>  
  2010-01-01
  2010-01-04
  2010-01-05
  2010-01-06
  2010-01-07
  2010-01-08

dateseq also works on times:

$ dateseq 12:00:00 5m 12:17:00
=>
  12:00:00
  12:05:00
  12:10:00
  12:15:00

and also date-times:

$ dateseq --compute-from-last 2012-01-02T12:00:00 5m 2012-01-02T12:17:00
=>
  2012-01-02T12:02:00
  2012-01-02T12:07:00
  2012-01-02T12:12:00
  2012-01-02T12:17:00

dateconv

A tool to convert dates between different calendric systems and/or time zones. While other such tools usually focus on converting Gregorian dates to, say, the Chinese calendar, dconv aims at supporting calendric systems which are essential in financial contexts.

To convert a (Gregorian) date into the so called ymcw representation:

$ dateconv 2012-03-04 -f "%Y-%m-%c-%w"
=>
  2012-03-01-00

and vice versa:

$ dateconv 2012-03-01-Sun -i "%Y-%m-%c-%a" -f '%F'
=>
  2012-03-04

where the ymcw representation means, the %c-th %w of the month in a given year. This is useful if dates are specified like, the third Thursday in May for instance.

dateconv can also be used to convert occurrences of dates, times or date-times in an input stream on the fly

$ dateconv -S -i '%b/%d %Y at %I:%M %P' <<EOF
Remember we meet on Mar/03 2012 at 02:30 pm
EOF
=>
  Remember we meet on 2012-03-03T14:30:00

and most prominently to convert between time zones:

$ dateconv --from-zone "America/Chicago" --zone "Asia/Tokyo" 2012-01-04T09:33:00
=>
  2012-01-05T00:33:00

$ dateconv --zone "America/Chicago" now -f "%d %b %Y %T"
=>
  05 Apr 2012 11:11:57

datetest

A tool to perform date comparison in the shell, it's modelled after test(1) but with proper command line options.

$ if datetest today --gt 2010-01-01; then
    echo "yes"
  fi
=>
  yes

dateadd

A tool to perform date arithmetic (date maths) in the shell. Given a date and a list of durations this will compute new dates. Given a duration and a list of dates this will compute new dates.

$ dateadd 2010-02-02 +4d
=>
  2010-02-06

$ dateadd 2010-02-02 +1w
=>
  2010-02-09

$ dateadd -1d <<EOF
2001-01-05
2001-01-01
EOF
=>
  2001-01-04
  2000-12-31

Adding durations to times:

$ dateadd 12:05:00 +10m
=>
  12:15:00

and even date-times:

$ dateadd 2012-03-12T12:05:00 -1d4h
=>
  2012-03-11T08:05:00

If supported by the system's zoneinfo database leap-second adjusted calculations are possible. Use the unit rs to denote "real" seconds:

$ dateadd '2012-06-30 23:59:30' +30rs
=>
  2012-06-30T23:59:60

as opposed to:

$ dateadd '2012-06-30 23:59:30' +30s
=>
  2012-07-01T00:00:00

datediff

A tool to calculate the difference between two (or more) dates. This is somewhat the converse of dadd. Outputs will be durations that, when added to the first date, give the second date.

Get the number of days between two dates:

$ datediff 2001-02-08 2001-03-02
=>
  22

The duration format can be controlled through the -f switch:

$ datediff 2001-02-08 2001-03-09 -f "%m month and %d day"
=>
  1 month and 1 day

datediff also accepts time stamps as input:

$ datediff 2012-03-01T12:17:00 2012-03-02T14:00:00
=>
  92580s

The -f switch does the right thing:

$ datediff 2012-03-01T12:17:00 2012-03-02T14:00:00 -f '%dd %Ss'
=>
  1d 6180s

compare to:

$ datediff 2012-03-01T12:17:00 2012-03-02T14:00:00 -f '%dd %Hh %Ss'
=>
  1d 1h 2580s

If supported by the system's zoneinfo database leap-second adjusted calculations can be made. Use the format specifier %rS to get the elapsed time in "real" seconds:

datediff '2012-06-30 23:59:30' '2012-07-01 00:00:30' -f '%rS'
=>
  61

dategrep

A tool to extract lines from an input stream that match certain criteria, showing either the line or the match:

$ dategrep '<2012-03-01' <<EOF
Feb 2012-02-28
Feb 2012-02-29  leap day
Mar 2012-03-01
Mar 2012-03-02
EOF
=>
  Feb   2012-02-28
  Feb   2012-02-29  leap day

dateround

A tool to "round" dates or time stamps to a recurring point in time, like the next/previous January or the next/previous Thursday.

Round (backwards) to the first of the current month:

$ dateround '2011-08-22' -1
=>
  2011-08-01

Round a stream of dates strictly to the next month's first:

$ dateround -S -n 1 <<EOF
pay cable   2012-02-28
pay gas 2012-02-29
pay rent    2012-03-01
redeem loan 2012-03-02
EOF
=>
  pay cable 2012-03-01
  pay gas   2012-03-01
  pay rent  2012-04-01
  redeem loan   2012-04-01

Round a timeseries to the next minute (i.e. the seconds part is 00) and then to the next half-past time (and convert to ISO):

$ dateround -S 0s30m -i '%d/%m/%Y %T' -f '%F %T' <<EOF
06/03/2012 14:27:12 eventA
06/03/2012 14:29:59 eventA
06/03/2012 14:30:00 eventB
06/03/2012 14:30:01 eventB
EOF
=>
  2012-03-06 14:30:00   eventA
  2012-03-06 14:30:00   eventA
  2012-03-06 14:30:00   eventB
  2012-03-06 15:30:00   eventB

Alternatively, if you divide the day into half-hours you can round to one of those using the co-class notation:

$ dateround -S /30m -i '%d/%m/%Y %T' -f '%F %T' <<EOF
06/03/2012 14:27:12 eventA
06/03/2012 14:29:59 eventA
06/03/2012 14:30:00 eventB
06/03/2012 14:30:01 eventB
EOF
=>
  2012-03-06 14:30:00   eventA
  2012-03-06 14:30:00   eventA
  2012-03-06 14:30:00   eventB
  2012-03-06 15:00:00   eventB

This is largely identical to the previous example except, that a full hour (being an even multiple of half-hours) is a possible rounding target.

datesort

New in the 0.3 series of dateutils. A tool to bring the lines of a file into chronological order.

$ datesort <<EOF
2009-06-03 caev="DVCA" secu="VOD" exch="XLON" xdte="2009-06-03" nett/GBX="5.2"
2011-11-16 caev="DVCA" secu="VOD" exch="XLON" xdte="2011-11-16" nett/GBX="3.05"
2013-11-20 caev="DVCA" secu="VOD" exch="XLON" xdte="2013-11-20" nett/GBX="3.53"
2012-06-06 caev="DVCA" secu="VOD" exch="XLON" xdte="2012-06-06" nett/GBX="6.47"
2013-06-12 caev="DVCA" secu="VOD" exch="XLON" xdte="2013-06-12" nett/GBX="6.92"
2010-11-17 caev="DVCA" secu="VOD" exch="XLON" xdte="2010-11-17" nett/GBX="2.85"
EOF
=>
  2009-06-03 caev="DVCA" secu="VOD" exch="XLON" xdte="2009-06-03" nett/GBX="5.2"
  2010-11-17 caev="DVCA" secu="VOD" exch="XLON" xdte="2010-11-17" nett/GBX="2.85"
  2011-11-16 caev="DVCA" secu="VOD" exch="XLON" xdte="2011-11-16" nett/GBX="3.05"
  2012-06-06 caev="DVCA" secu="VOD" exch="XLON" xdte="2012-06-06" nett/GBX="6.47"
  2013-06-12 caev="DVCA" secu="VOD" exch="XLON" xdte="2013-06-12" nett/GBX="6.92"
  2013-11-20 caev="DVCA" secu="VOD" exch="XLON" xdte="2013-11-20" nett/GBX="3.53"

At the moment the datesort tool is built upon sort(1) and cut(1).

datezone

New in the 0.3 series of dateutils. A tool to quickly inspect date/time values in different timezones. The result will be a matrix that shows every date-time value in every timezone:

$ datezone Europe/Berlin Australia/Sydney now 2014-06-30T05:00:00
=>
  2014-01-30T17:37:13+01:00 Europe/Berlin
  2014-01-31T03:37:13+11:00 Australia/Sydney
  2014-06-30T07:00:00+02:00 Europe/Berlin
  2014-06-30T15:00:00+10:00 Australia/Sydney

The datezone tool can also be used to obtain the next or previous DST transition relative to a given date/time:

$ datezone --next Europe/Berlin Australia/Sydney 2013-02-19
=>
  2013-03-31T02:00:00+01:00 -> 2013-03-31T03:00:00+02:00    Europe/Berlin
  2013-04-07T03:00:00+11:00 -> 2013-04-07T02:00:00+10:00    Australia/Sydney

where the left time stamp denotes the current zone offset and the right side is the zone offset after the transition. The date/time indicates the exact moment when the transition is about to take place.

In essence datezone is a better zdump(1).

strptime

A tool that brings the flexibility of strptime(3) to the command line. While date(1) has support for output formats, it lacks any kind of support to read arbitrary input from the domain of dates, in particular when the input format is specifically known beforehand and only matching dates/times shall be considered.

Usually, to print something like Mon, May-01/2000 in ISO 8601, people come up with the most prolific recommendations like using perl or sed or awk or any two of them, or they come up with a pageful of shell code full of bashisms, and when sufficiently pestered they "improve" their variant to a dozen pages of portable shell code.

The strptime tool does the job just fine

strptime -i "%a, %b-%d/%Y" "Mon, May-01/2000"
=>
  2000-05-01

just like you would have done in C.

Similar projects

In no particular order and without any claim to completeness:

Use the one that best fits your purpose. And in case you happen to like mine, vote: dateutils' openhub page

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