1CONVCAL(1)                       User's Manual                      CONVCAL(1)
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NAME

6       convcal - convert dates to different formats
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SYNOPSIS

10       convcal [OPTIONS] [DATE]
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DESCRIPTION

14       convcal  is part of the grace software package, an application for two-
15       dimensional data visualization. convcal converts dates from and to var‐
16       ious  formats.  The following date formats are supported (hour, minutes
17       and seconds are always optional):
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20       iso    1999-12-31T23:59:59.999
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22       european
23              31/12/1999 23:59:59.999 or 31/12/99 23:59:59.999
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25       us     12/31/1999 23:59:59.999 or 12/31/99 23:59:59.999
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27       days   123456.789
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29       seconds
30              123456.789
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34       The formats are tried in the following order  :  users's  choice,  iso,
35       european  and  us  (there  is no ambiguity between calendar formats and
36       numerical formats and therefore no order is specified for them).
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USAGE

40       convcal reads the dates either on the command line or in  the  standard
41       input if the command line contains no date.
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43       The  user's choice for the input format put one format before the other
44       ones in the trial list, this is mainly  useful  for  US  citizen  which
45       would  certainly  prefer to have US format checked before european for‐
46       mat. The default user's choice (nohint) does nothing so  the  following
47       formats of the list are checked.
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49       The separators between various fields can be any characters in the set:
50       " :/.-T". One or more spaces act as one separator, other characters can
51       not be repeated, the T separator is allowed only between date and time,
52       mainly for iso8601. So the string "1999-12 31:23-59"  is  allowed  (but
53       not recommended).  The '-' character is used both as a separator (it is
54       traditionally used in iso8601 format) and as the unary minus (for dates
55       in the far past or for numerical dates). When the year is between 0 and
56       99 and is written with two or less digits, it  is  mapped  to  the  era
57       beginning at wrap year and ending at wrap year + 99 as follows :
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59       [wy ; 99] -> [ wrap_year ; 100*(1 + wrap_year/100) - 1 ]
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61       [00 ; wy-1] -> [ 100*(1 + wrap_year/100) ; wrap_year + 99]
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63       so  for  example  if the wrap year is set to 1950 (which is the default
64       value), then the mapping is :
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66       range [00 ; 49] is mapped to [2000 ; 2049]
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68       range [50 ; 99] is mapped to [1950 ; 1999]
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70       this is reasonably Y2K compliant and is consistent  with  current  use.
71       Specifying  year 1 is still possible using more than two digits as fol‐
72       lows : "0001-03-04" is unambiguously March the 4th, year 1, even if the
73       user's choice is us format. However using two digits only is not recom‐
74       mended (we introduce a 2050 bug here so this feature should be  removed
75       at some point in the future ;-)
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77       Numerical dates (days and seconds formats) can be specified using inte‐
78       ger, real or exponential formats (the 'd' and 'D' exponant markers from
79       fortran  are  supported in addition to 'e' and 'E').  They are computed
80       according to a customizable reference date.  The default value is given
81       by  the REFDATE constant in the source file.  You can change this value
82       as you want before compiling, and you can change it at will  using  the
83       -r  command  line  option. The default value in the distributed file is
84       "-4713-01-01T12:00:00", it is a classical  reference  for  astronomical
85       events  (note  that the '-' is used here both as a unary minus and as a
86       separator).
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88       The program can be used either for Denys's and gregorian calendars.  It
89       does  not  take into account leap seconds : you can think it works only
90       in International Atomic Time (TAI) and not in Coordinated Unified  Time
91       (UTC)  ...   Inexistant  dates are detected, they include year 0, dates
92       between 1582-10-05 and 1582-10-14, February 29th  of  non  leap  years,
93       months below 1 or above 12, ...
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OPTIONS

97       A summary of the options supported by convcal is included below.
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100       -h     prints the help message on stderr and exits successfully
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102       -i format
103              set  user's  choice for input format, supported formats are iso,
104              european, us, days, seconds and nohint.  At  the  beginning  the
105              input format is nohint, which means the program try to guess the
106              format by itself, if the user's choice does not allow  to  parse
107              the date, other formats are tried
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109       -o format
110              force  output  format,  supported formats are iso, european, us,
111              days, seconds and nohint.  At the beginning, the  output  format
112              is  nohint,  which  means the program uses days format for dates
113              read in any calendar format and uses iso8601 for dates  read  in
114              numerical format
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116       -r date
117              set  reference  date  (the  date is read using the current input
118              format) at the beginning the reference is set according  to  the
119              REFDATE  constant  in the code, which is -4713-01-01T12:00:00 in
120              the distributed file.
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122       -w year
123              set the wrap year to year
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SEE ALSO

127       grace(1)
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129       http://plasma-gate.weizmann.ac.il/Grace/
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AUTHOR

133       Luc Maisonobe
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135       This man-page was written by Jan Schaumann <jschauma@netmeister.org> as
136       part  of  "The  Missing Man Pages Project".  Please see http://www.net
137       meister.org/misc/m2p2/index.html for details.
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141grace                           August 11, 2001                     CONVCAL(1)
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