convdate - Convert time/date strings and numbers

convdate [-dhl] [-c | -n | -s] [date ...]

convdate translates the date/time strings given on the command line, outputting the results one to a line. The input can either be a date in some format that parsedate(3) can parse or the number of seconds since epoch (if -c is given). The output is either ctime(3) results, the number of seconds since epoch, or a Usenet Date: header, depending on the options given.

-c

Each argument is taken to be the number of seconds since epoch (a time_t) rather than a date.

-d

Output a valid Usenet Date: header instead of the results of ctime(3) for each date given on the command line. This is useful for testing the algorithm used to generate Date: headers for local posts. Normally, the date will be in UTC, but see the -l option.

-h

Print usage information and exit.

-l

Only makes sense in combination with -d. If given, Date: headers generated will use the local time zone instead of UTC.

-n

Rather than outputting the results of ctime(3) or a Date: header, output each date given as the number of seconds since epoch (a time_t). This option doesn't make sense in combination with -d.

-s

Pass each given date to parsedate(3) and print the results of ctime(3) (or a Date: header if -d is given). This is the default behavior.

Note that relative times or times with partial information use the current time to fill in the rest of the date, so dates like 12pm are taken to be 12pm of the day when convdate is run. This is a property of parsedate(3); see the man page for more information. Most of these examples are from the original man page dating from 1991 and were run in the -0400 time zone.

    % convdate 'feb 10 10am'
    Sun Feb 10 10:00:00 1991

    % convdate 12pm 5/4/90
    Fri Dec 13 00:00:00 1991
    Fri May  4 00:00:00 1990

Note that 12pm and 5/4/90 are two *separate* arguments and therefore result in two results. Note also that a date with no time is taken to be at midnight.

    % convdate -n 'feb 10 10am' '12pm 5/4/90'
    666198000
    641880000

    % convdate -c 666198000
    Sun Feb 10 10:00:00 1991

ctime(3) results are in the local time zone. Compare to:

    % convdate -dc 666198000
    Sun, 10 Feb 1991 15:00:00 +0000 (UTC)

    % env TZ=PST8PDT convdate -dlc 666198000
    Sun, 10 Feb 1991 07:00:00 -0800 (PST)

    % env TZ=EST5EDT convdate -dlc 666198000
    Sun, 10 Feb 1991 10:00:00 -0500 (EST)

The system library functions generally use the environment variable TZ to determine (or at least override) the local time zone.

Written by Rich CW$alz <rsalz@uunet.uu.net>, rewritten and updated by Russ Allbery <rra@stanford.edu> for the -d and -l flags.

$Id: convdate.1,v 1.5 2002/02/22 20:39:04 vinocur Exp $

parsedate(3).