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tabdate - Convert a date/time column


tabdate in_file out_file in_format out_format


tabdate converts a file with the string representation of one date format into another. It is simply a wrapper of strptime(4) to strftime(4) .


The following parameters are recognized in any order if the keyword is also given:
input file name(s). No default.
output file name. No default.
format to read with. The field descriptors are explained in strptime(3) and date(1) . No default.
format to write with. No default.
Column to use for the input date/time. If none supplied (or 0 used), the whole line will be used to extract the time from. This might be useful if the date and time are in separate columns. Default: 0
If given, this will be the format (as used by format1=) to reference the time to. The output is now forced to be format0=%s, i.e. number of seconds since time0. The special value 0 is used to define the reference time as the first timestamp in the file. Default: none.
Scale factor used when a time0= is used, and by which the time in seconds since time0 is divided to get more reasonable units. Default: 1


Although the field descriptors are described in e.g.strptime(3) and date(1) , here is a very brief summary of the common ones:
%a,%A    weekday name
%b,%B,%h    month name
%c    full date and time
%C    century number (0-99)
%d,%e    day in month (0-31)
%D    Equivalent  to  %m/%d/%y
%H    hour (0-23)
%j    day number in year (1-366)
%m    month number (1-12)
%M    minute (0-59)
%S    second (0-60),60 is for a leap second
%T    Equivalent to %H:%M:%S
%y    year within century (0-99)
%Y    full year, e.g. 1991


  % echo ’2001-11-12 18:31:01’ | tabdate - - ’%Y-%m-%d %H:%M:%S’ ’%c’
  Mon Nov 12 18:31:01 2001
  % date +%s | tabdate - - %s %c
  Mon May  9 16:16:06 2005
and a contrived way to turn time into seconds
  tabdate tab0 - %T "1970 %T" | tabdate - - "%Y %T" %s
and here an example to find the number of seconds between two time-stamps:
  % set t0="‘date +%s‘"
  % set t1="‘date +%s‘"
  % printf "%s0s0 "$a"  "$b" | tabdate - - "%c" %s time0=0


Cannot handle fractional seconds.

See Also

date(1) , strptime(3) , strftime(3)


src/kernel/tab    tabdate.c


Peter Teuben

Update History

1-Feb-05    V0.1 Created    PJT
9-may-05    V0.2 added a working time0= and future tcol=    PJT
4-apr-09    V0.3 added dcol= (instead of tcol=), fixed initializtion    PJT

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