1: @c GNU date syntax documentation
    2: 
    3: @c Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
    4: @c 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
    5: 
    6: @c Permission is granted to copy, distribute and/or modify this document
    7: @c under the terms of the GNU Free Documentation License, Version 1.2 or
    8: @c any later version published by the Free Software Foundation; with no
    9: @c Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
   10: @c Texts.  A copy of the license is included in the ``GNU Free
   11: @c Documentation License'' file as part of this distribution.
   12: 
   13: @node Date input formats
   14: @chapter Date input formats
   15: 
   16: @cindex date input formats
   17: @findex get_date
   18: 
   19: First, a quote:
   20: 
   21: @quotation
   22: Our units of temporal measurement, from seconds on up to months, are so
   23: complicated, asymmetrical and disjunctive so as to make coherent mental
   24: reckoning in time all but impossible.  Indeed, had some tyrannical god
   25: contrived to enslave our minds to time, to make it all but impossible
   26: for us to escape subjection to sodden routines and unpleasant surprises,
   27: he could hardly have done better than handing down our present system.
   28: It is like a set of trapezoidal building blocks, with no vertical or
   29: horizontal surfaces, like a language in which the simplest thought
   30: demands ornate constructions, useless particles and lengthy
   31: circumlocutions.  Unlike the more successful patterns of language and
   32: science, which enable us to face experience boldly or at least
   33: level-headedly, our system of temporal calculation silently and
   34: persistently encourages our terror of time.
   35: 
   36: @dots{}  It is as though architects had to measure length in feet, width
   37: in meters and height in ells; as though basic instruction manuals
   38: demanded a knowledge of five different languages.  It is no wonder then
   39: that we often look into our own immediate past or future, last Tuesday
   40: or a week from Sunday, with feelings of helpless confusion.  @dots{}
   41: 
   42: --- Robert Grudin, @cite{Time and the Art of Living}.
   43: @end quotation
   44: 
   45: This section describes the textual date representations that @sc{gnu}
   46: programs accept.  These are the strings you, as a user, can supply as
   47: arguments to the various programs.  The C interface (via the
   48: @code{get_date} function) is not described here.
   49: 
   50: @menu
   51: * General date syntax::            Common rules.
   52: * Calendar date items::            19 Dec 1994.
   53: * Time of day items::              9:20pm.
   54: * Time zone items::                @sc{est}, @sc{pdt}, @sc{gmt}.
   55: * Day of week items::              Monday and others.
   56: * Relative items in date strings:: next tuesday, 2 years ago.
   57: * Pure numbers in date strings::   19931219, 1440.
   58: * Seconds since the Epoch::        @@1078100502.
   59: * Specifying time zone rules::     TZ="America/New_York", TZ="UTC0".
   60: * Authors of get_date::            Bellovin, Eggert, Salz, Berets, et al.
   61: @end menu
   62: 
   63: 
   64: @node General date syntax
   65: @section General date syntax
   66: 
   67: @cindex general date syntax
   68: 
   69: @cindex items in date strings
   70: A @dfn{date} is a string, possibly empty, containing many items
   71: separated by whitespace.  The whitespace may be omitted when no
   72: ambiguity arises.  The empty string means the beginning of today (i.e.,
   73: midnight).  Order of the items is immaterial.  A date string may contain
   74: many flavors of items:
   75: 
   76: @itemize @bullet
   77: @item calendar date items
   78: @item time of day items
   79: @item time zone items
   80: @item day of the week items
   81: @item relative items
   82: @item pure numbers.
   83: @end itemize
   84: 
   85: @noindent We describe each of these item types in turn, below.
   86: 
   87: @cindex numbers, written-out
   88: @cindex ordinal numbers
   89: @findex first @r{in date strings}
   90: @findex next @r{in date strings}
   91: @findex last @r{in date strings}
   92: A few ordinal numbers may be written out in words in some contexts.  This is
   93: most useful for specifying day of the week items or relative items (see
   94: below).  Among the most commonly used ordinal numbers, the word
   95: @samp{last} stands for @math{-1}, @samp{this} stands for 0, and
   96: @samp{first} and @samp{next} both stand for 1.  Because the word
   97: @samp{second} stands for the unit of time there is no way to write the
   98: ordinal number 2, but for convenience @samp{third} stands for 3,
   99: @samp{fourth} for 4, @samp{fifth} for 5,
  100: @samp{sixth} for 6, @samp{seventh} for 7, @samp{eighth} for 8,
  101: @samp{ninth} for 9, @samp{tenth} for 10, @samp{eleventh} for 11 and
  102: @samp{twelfth} for 12.
  103: 
  104: @cindex months, written-out
  105: When a month is written this way, it is still considered to be written
  106: numerically, instead of being ``spelled in full''; this changes the
  107: allowed strings.
  108: 
  109: @cindex language, in dates
  110: In the current implementation, only English is supported for words and
  111: abbreviations like @samp{AM}, @samp{DST}, @samp{EST}, @samp{first},
  112: @samp{January}, @samp{Sunday}, @samp{tomorrow}, and @samp{year}.
  113: 
  114: @cindex language, in dates
  115: @cindex time zone item
  116: The output of the @command{date} command
  117: is not always acceptable as a date string,
  118: not only because of the language problem, but also because there is no
  119: standard meaning for time zone items like @samp{IST}.  When using
  120: @command{date} to generate a date string intended to be parsed later,
  121: specify a date format that is independent of language and that does not
  122: use time zone items other than @samp{UTC} and @samp{Z}.  Here are some
  123: ways to do this:
  124: 
  125: @example
  126: $ LC_ALL=C TZ=UTC0 date
  127: Mon Mar  1 00:21:42 UTC 2004
  128: $ TZ=UTC0 date +'%Y-%m-%d %H:%M:%SZ'
  129: 2004-03-01 00:21:42Z
  130: $ date --iso-8601=ns | tr T ' '  # --iso-8601 is a GNU extension.
  131: 2004-02-29 16:21:42,692722128-0800
  132: $ date --rfc-2822  # a GNU extension
  133: Sun, 29 Feb 2004 16:21:42 -0800
  134: $ date +'%Y-%m-%d %H:%M:%S %z'  # %z is a GNU extension.
  135: 2004-02-29 16:21:42 -0800
  136: $ date +'@@%s.%N'  # %s and %N are GNU extensions.
  137: @@1078100502.692722128
  138: @end example
  139: 
  140: @cindex case, ignored in dates
  141: @cindex comments, in dates
  142: Alphabetic case is completely ignored in dates.  Comments may be introduced
  143: between round parentheses, as long as included parentheses are properly
  144: nested.  Hyphens not followed by a digit are currently ignored.  Leading
  145: zeros on numbers are ignored.
  146: 
  147: Invalid dates like @samp{2005-02-29} or times like @samp{24:00} are
  148: rejected.  In the typical case of a host that does not support leap
  149: seconds, a time like @samp{23:59:60} is rejected even if it
  150: corresponds to a valid leap second.
  151: 
  152: 
  153: @node Calendar date items
  154: @section Calendar date items
  155: 
  156: @cindex calendar date item
  157: 
  158: A @dfn{calendar date item} specifies a day of the year.  It is
  159: specified differently, depending on whether the month is specified
  160: numerically or literally.  All these strings specify the same calendar date:
  161: 
  162: @example
  163: 1972-09-24     # @sc{iso} 8601.
  164: 72-9-24        # Assume 19xx for 69 through 99,
  165:                # 20xx for 00 through 68.
  166: 72-09-24       # Leading zeros are ignored.
  167: 9/24/72        # Common U.S. writing.
  168: 24 September 1972
  169: 24 Sept 72     # September has a special abbreviation.
  170: 24 Sep 72      # Three-letter abbreviations always allowed.
  171: Sep 24, 1972
  172: 24-sep-72
  173: 24sep72
  174: @end example
  175: 
  176: The year can also be omitted.  In this case, the last specified year is
  177: used, or the current year if none.  For example:
  178: 
  179: @example
  180: 9/24
  181: sep 24
  182: @end example
  183: 
  184: Here are the rules.
  185: 
  186: @cindex @sc{iso} 8601 date format
  187: @cindex date format, @sc{iso} 8601
  188: For numeric months, the @sc{iso} 8601 format
  189: @samp{@var{year}-@var{month}-@var{day}} is allowed, where @var{year} is
  190: any positive number, @var{month} is a number between 01 and 12, and
  191: @var{day} is a number between 01 and 31.  A leading zero must be present
  192: if a number is less than ten.  If @var{year} is 68 or smaller, then 2000
  193: is added to it; otherwise, if @var{year} is less than 100,
  194: then 1900 is added to it.  The construct
  195: @samp{@var{month}/@var{day}/@var{year}}, popular in the United States,
  196: is accepted.  Also @samp{@var{month}/@var{day}}, omitting the year.
  197: 
  198: @cindex month names in date strings
  199: @cindex abbreviations for months
  200: Literal months may be spelled out in full: @samp{January},
  201: @samp{February}, @samp{March}, @samp{April}, @samp{May}, @samp{June},
  202: @samp{July}, @samp{August}, @samp{September}, @samp{October},
  203: @samp{November} or @samp{December}.  Literal months may be abbreviated
  204: to their first three letters, possibly followed by an abbreviating dot.
  205: It is also permitted to write @samp{Sept} instead of @samp{September}.
  206: 
  207: When months are written literally, the calendar date may be given as any
  208: of the following:
  209: 
  210: @example
  211: @var{day} @var{month} @var{year}
  212: @var{day} @var{month}
  213: @var{month} @var{day} @var{year}
  214: @var{day}-@var{month}-@var{year}
  215: @end example
  216: 
  217: Or, omitting the year:
  218: 
  219: @example
  220: @var{month} @var{day}
  221: @end example
  222: 
  223: 
  224: @node Time of day items
  225: @section Time of day items
  226: 
  227: @cindex time of day item
  228: 
  229: A @dfn{time of day item} in date strings specifies the time on a given
  230: day.  Here are some examples, all of which represent the same time:
  231: 
  232: @example
  233: 20:02:00.000000
  234: 20:02
  235: 8:02pm
  236: 20:02-0500      # In @sc{est} (U.S. Eastern Standard Time).
  237: @end example
  238: 
  239: More generally, the time of day may be given as
  240: @samp{@var{hour}:@var{minute}:@var{second}}, where @var{hour} is
  241: a number between 0 and 23, @var{minute} is a number between 0 and
  242: 59, and @var{second} is a number between 0 and 59 possibly followed by
  243: @samp{.} or @samp{,} and a fraction containing one or more digits.
  244: Alternatively,
  245: @samp{:@var{second}} can be omitted, in which case it is taken to
  246: be zero.  On the rare hosts that support leap seconds, @var{second}
  247: may be 60.
  248: 
  249: @findex am @r{in date strings}
  250: @findex pm @r{in date strings}
  251: @findex midnight @r{in date strings}
  252: @findex noon @r{in date strings}
  253: If the time is followed by @samp{am} or @samp{pm} (or @samp{a.m.}
  254: or @samp{p.m.}), @var{hour} is restricted to run from 1 to 12, and
  255: @samp{:@var{minute}} may be omitted (taken to be zero).  @samp{am}
  256: indicates the first half of the day, @samp{pm} indicates the second
  257: half of the day.  In this notation, 12 is the predecessor of 1:
  258: midnight is @samp{12am} while noon is @samp{12pm}.
  259: (This is the zero-oriented interpretation of @samp{12am} and @samp{12pm},
  260: as opposed to the old tradition derived from Latin
  261: which uses @samp{12m} for noon and @samp{12pm} for midnight.)
  262: 
  263: @cindex time zone correction
  264: @cindex minutes, time zone correction by
  265: The time may alternatively be followed by a time zone correction,
  266: expressed as @samp{@var{s}@var{hh}@var{mm}}, where @var{s} is @samp{+}
  267: or @samp{-}, @var{hh} is a number of zone hours and @var{mm} is a number
  268: of zone minutes.  You can also separate @var{hh} from @var{mm} with a colon.
  269: When a time zone correction is given this way, it
  270: forces interpretation of the time relative to
  271: Coordinated Universal Time (@sc{utc}), overriding any previous
  272: specification for the time zone or the local time zone.  For example,
  273: @samp{+0530} and @samp{+05:30} both stand for the time zone 5.5 hours
  274: ahead of @sc{utc} (e.g., India).  The @var{minute}
  275: part of the time of day may not be elided when a time zone correction
  276: is used.  This is the best way to specify a time zone correction by
  277: fractional parts of an hour.
  278: 
  279: Either @samp{am}/@samp{pm} or a time zone correction may be specified,
  280: but not both.
  281: 
  282: 
  283: @node Time zone items
  284: @section Time zone items
  285: 
  286: @cindex time zone item
  287: 
  288: A @dfn{time zone item} specifies an international time zone, indicated
  289: by a small set of letters, e.g., @samp{UTC} or @samp{Z}
  290: for Coordinated Universal
  291: Time.  Any included periods are ignored.  By following a
  292: non-daylight-saving time zone by the string @samp{DST} in a separate
  293: word (that is, separated by some white space), the corresponding
  294: daylight saving time zone may be specified.
  295: Alternatively, a non-daylight-saving time zone can be followed by a
  296: time zone correction, to add the two values.  This is normally done
  297: only for @samp{UTC}; for example, @samp{UTC+05:30} is equivalent to
  298: @samp{+05:30}.
  299: 
  300: Time zone items other than @samp{UTC} and @samp{Z}
  301: are obsolescent and are not recommended, because they
  302: are ambiguous; for example, @samp{EST} has a different meaning in
  303: Australia than in the United States.  Instead, it's better to use
  304: unambiguous numeric time zone corrections like @samp{-0500}, as
  305: described in the previous section.
  306: 
  307: If neither a time zone item nor a time zone correction is supplied,
  308: time stamps are interpreted using the rules of the default time zone
  309: (@pxref{Specifying time zone rules}).
  310: 
  311: 
  312: @node Day of week items
  313: @section Day of week items
  314: 
  315: @cindex day of week item
  316: 
  317: The explicit mention of a day of the week will forward the date
  318: (only if necessary) to reach that day of the week in the future.
  319: 
  320: Days of the week may be spelled out in full: @samp{Sunday},
  321: @samp{Monday}, @samp{Tuesday}, @samp{Wednesday}, @samp{Thursday},
  322: @samp{Friday} or @samp{Saturday}.  Days may be abbreviated to their
  323: first three letters, optionally followed by a period.  The special
  324: abbreviations @samp{Tues} for @samp{Tuesday}, @samp{Wednes} for
  325: @samp{Wednesday} and @samp{Thur} or @samp{Thurs} for @samp{Thursday} are
  326: also allowed.
  327: 
  328: @findex next @var{day}
  329: @findex last @var{day}
  330: A number may precede a day of the week item to move forward
  331: supplementary weeks.  It is best used in expression like @samp{third
  332: monday}.  In this context, @samp{last @var{day}} or @samp{next
  333: @var{day}} is also acceptable; they move one week before or after
  334: the day that @var{day} by itself would represent.
  335: 
  336: A comma following a day of the week item is ignored.
  337: 
  338: 
  339: @node Relative items in date strings
  340: @section Relative items in date strings
  341: 
  342: @cindex relative items in date strings
  343: @cindex displacement of dates
  344: 
  345: @dfn{Relative items} adjust a date (or the current date if none) forward
  346: or backward.  The effects of relative items accumulate.  Here are some
  347: examples:
  348: 
  349: @example
  350: 1 year
  351: 1 year ago
  352: 3 years
  353: 2 days
  354: @end example
  355: 
  356: @findex year @r{in date strings}
  357: @findex month @r{in date strings}
  358: @findex fortnight @r{in date strings}
  359: @findex week @r{in date strings}
  360: @findex day @r{in date strings}
  361: @findex hour @r{in date strings}
  362: @findex minute @r{in date strings}
  363: The unit of time displacement may be selected by the string @samp{year}
  364: or @samp{month} for moving by whole years or months.  These are fuzzy
  365: units, as years and months are not all of equal duration.  More precise
  366: units are @samp{fortnight} which is worth 14 days, @samp{week} worth 7
  367: days, @samp{day} worth 24 hours, @samp{hour} worth 60 minutes,
  368: @samp{minute} or @samp{min} worth 60 seconds, and @samp{second} or
  369: @samp{sec} worth one second.  An @samp{s} suffix on these units is
  370: accepted and ignored.
  371: 
  372: @findex ago @r{in date strings}
  373: The unit of time may be preceded by a multiplier, given as an optionally
  374: signed number.  Unsigned numbers are taken as positively signed.  No
  375: number at all implies 1 for a multiplier.  Following a relative item by
  376: the string @samp{ago} is equivalent to preceding the unit by a
  377: multiplier with value @math{-1}.
  378: 
  379: @findex day @r{in date strings}
  380: @findex tomorrow @r{in date strings}
  381: @findex yesterday @r{in date strings}
  382: The string @samp{tomorrow} is worth one day in the future (equivalent
  383: to @samp{day}), the string @samp{yesterday} is worth
  384: one day in the past (equivalent to @samp{day ago}).
  385: 
  386: @findex now @r{in date strings}
  387: @findex today @r{in date strings}
  388: @findex this @r{in date strings}
  389: The strings @samp{now} or @samp{today} are relative items corresponding
  390: to zero-valued time displacement, these strings come from the fact
  391: a zero-valued time displacement represents the current time when not
  392: otherwise changed by previous items.  They may be used to stress other
  393: items, like in @samp{12:00 today}.  The string @samp{this} also has
  394: the meaning of a zero-valued time displacement, but is preferred in
  395: date strings like @samp{this thursday}.
  396: 
  397: When a relative item causes the resulting date to cross a boundary
  398: where the clocks were adjusted, typically for daylight saving time,
  399: the resulting date and time are adjusted accordingly.
  400: 
  401: The fuzz in units can cause problems with relative items.  For
  402: example, @samp{2003-07-31 -1 month} might evaluate to 2003-07-01,
  403: because 2003-06-31 is an invalid date.  To determine the previous
  404: month more reliably, you can ask for the month before the 15th of the
  405: current month.  For example:
  406: 
  407: @example
  408: $ date -R
  409: Thu, 31 Jul 2003 13:02:39 -0700
  410: $ date --date='-1 month' +'Last month was %B?'
  411: Last month was July?
  412: $ date --date="$(date +%Y-%m-15) -1 month" +'Last month was %B!'
  413: Last month was June!
  414: @end example
  415: 
  416: Also, take care when manipulating dates around clock changes such as
  417: daylight saving leaps.  In a few cases these have added or subtracted
  418: as much as 24 hours from the clock, so it is often wise to adopt
  419: universal time by setting the @env{TZ} environment variable to
  420: @samp{UTC0} before embarking on calendrical calculations.
  421: 
  422: @node Pure numbers in date strings
  423: @section Pure numbers in date strings
  424: 
  425: @cindex pure numbers in date strings
  426: 
  427: The precise interpretation of a pure decimal number depends
  428: on the context in the date string.
  429: 
  430: If the decimal number is of the form @var{yyyy}@var{mm}@var{dd} and no
  431: other calendar date item (@pxref{Calendar date items}) appears before it
  432: in the date string, then @var{yyyy} is read as the year, @var{mm} as the
  433: month number and @var{dd} as the day of the month, for the specified
  434: calendar date.
  435: 
  436: If the decimal number is of the form @var{hh}@var{mm} and no other time
  437: of day item appears before it in the date string, then @var{hh} is read
  438: as the hour of the day and @var{mm} as the minute of the hour, for the
  439: specified time of day.  @var{mm} can also be omitted.
  440: 
  441: If both a calendar date and a time of day appear to the left of a number
  442: in the date string, but no relative item, then the number overrides the
  443: year.
  444: 
  445: 
  446: @node Seconds since the Epoch
  447: @section Seconds since the Epoch
  448: 
  449: If you precede a number with @samp{@@}, it represents an internal time
  450: stamp as a count of seconds.  The number can contain an internal
  451: decimal point (either @samp{.} or @samp{,}); any excess precision not
  452: supported by the internal representation is truncated toward minus
  453: infinity.  Such a number cannot be combined with any other date
  454: item, as it specifies a complete time stamp.
  455: 
  456: @cindex beginning of time, for @acronym{POSIX}
  457: @cindex epoch, for @acronym{POSIX}
  458: Internally, computer times are represented as a count of seconds since
  459: an epoch---a well-defined point of time.  On @acronym{GNU} and
  460: @acronym{POSIX} systems, the epoch is 1970-01-01 00:00:00 @sc{utc}, so
  461: @samp{@@0} represents this time, @samp{@@1} represents 1970-01-01
  462: 00:00:01 @sc{utc}, and so forth.  @acronym{GNU} and most other
  463: @acronym{POSIX}-compliant systems support such times as an extension
  464: to @acronym{POSIX}, using negative counts, so that @samp{@@-1}
  465: represents 1969-12-31 23:59:59 @sc{utc}.
  466: 
  467: Traditional Unix systems count seconds with 32-bit two's-complement
  468: integers and can represent times from 1901-12-13 20:45:52 through
  469: 2038-01-19 03:14:07 @sc{utc}.  More modern systems use 64-bit counts
  470: of seconds with nanosecond subcounts, and can represent all the times
  471: in the known lifetime of the universe to a resolution of 1 nanosecond.
  472: 
  473: On most hosts, these counts ignore the presence of leap seconds.
  474: For example, on most hosts @samp{@@915148799} represents 1998-12-31
  475: 23:59:59 @sc{utc}, @samp{@@915148800} represents 1999-01-01 00:00:00
  476: @sc{utc}, and there is no way to represent the intervening leap second
  477: 1998-12-31 23:59:60 @sc{utc}.
  478: 
  479: @node Specifying time zone rules
  480: @section Specifying time zone rules
  481: 
  482: @vindex TZ
  483: Normally, dates are interpreted using the rules of the current time
  484: zone, which in turn are specified by the @env{TZ} environment
  485: variable, or by a system default if @env{TZ} is not set.  To specify a
  486: different set of default time zone rules that apply just to one date,
  487: start the date with a string of the form @samp{TZ="@var{rule}"}.  The
  488: two quote characters (@samp{"}) must be present in the date, and any
  489: quotes or backslashes within @var{rule} must be escaped by a
  490: backslash.
  491: 
  492: For example, with the @acronym{GNU} @command{date} command you can
  493: answer the question ``What time is it in New York when a Paris clock
  494: shows 6:30am on October 31, 2004?'' by using a date beginning with
  495: @samp{TZ="Europe/Paris"} as shown in the following shell transcript:
  496: 
  497: @example
  498: $ export TZ="America/New_York"
  499: $ date --date='TZ="Europe/Paris" 2004-10-31 06:30'
  500: Sun Oct 31 01:30:00 EDT 2004
  501: @end example
  502: 
  503: In this example, the @option{--date} operand begins with its own
  504: @env{TZ} setting, so the rest of that operand is processed according
  505: to @samp{Europe/Paris} rules, treating the string @samp{2004-10-31
  506: 06:30} as if it were in Paris.  However, since the output of the
  507: @command{date} command is processed according to the overall time zone
  508: rules, it uses New York time.  (Paris was normally six hours ahead of
  509: New York in 2004, but this example refers to a brief Halloween period
  510: when the gap was five hours.)
  511: 
  512: A @env{TZ} value is a rule that typically names a location in the
  513: @uref{http://www.twinsun.com/tz/tz-link.htm, @samp{tz} database}.
  514: A recent catalog of location names appears in the
  515: @uref{http://twiki.org/cgi-bin/xtra/tzdate, TWiki Date and Time
  516: Gateway}.  A few non-@acronym{GNU} hosts require a colon before a
  517: location name in a @env{TZ} setting, e.g.,
  518: @samp{TZ=":America/New_York"}.
  519: 
  520: The @samp{tz} database includes a wide variety of locations ranging
  521: from @samp{Arctic/Longyearbyen} to @samp{Antarctica/South_Pole}, but
  522: if you are at sea and have your own private time zone, or if you are
  523: using a non-@acronym{GNU} host that does not support the @samp{tz}
  524: database, you may need to use a @acronym{POSIX} rule instead.  Simple
  525: @acronym{POSIX} rules like @samp{UTC0} specify a time zone without
  526: daylight saving time; other rules can specify simple daylight saving
  527: regimes.  @xref{TZ Variable,, Specifying the Time Zone with @code{TZ},
  528: libc, The GNU C Library}.
  529: 
  530: @node Authors of get_date
  531: @section Authors of @code{get_date}
  532: 
  533: @cindex authors of @code{get_date}
  534: 
  535: @cindex Bellovin, Steven M.
  536: @cindex Salz, Rich
  537: @cindex Berets, Jim
  538: @cindex MacKenzie, David
  539: @cindex Meyering, Jim
  540: @cindex Eggert, Paul
  541: @code{get_date} was originally implemented by Steven M. Bellovin
  542: (@email{smb@@research.att.com}) while at the University of North Carolina
  543: at Chapel Hill.  The code was later tweaked by a couple of people on
  544: Usenet, then completely overhauled by Rich $alz (@email{rsalz@@bbn.com})
  545: and Jim Berets (@email{jberets@@bbn.com}) in August, 1990.  Various
  546: revisions for the @sc{gnu} system were made by David MacKenzie, Jim Meyering,
  547: Paul Eggert and others.
  548: 
  549: @cindex Pinard, F.
  550: @cindex Berry, K.
  551: This chapter was originally produced by Fran@,{c}ois Pinard
  552: (@email{pinard@@iro.umontreal.ca}) from the @file{getdate.y} source code,
  553: and then edited by K.@: Berry (@email{kb@@cs.umb.edu}).