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clock(3,n)(n)                     Tcl Built-In Commands                    clock(3,n)(n)



NAME
       clock(3,n) - Obtain and manipulate time(1,2,n)

SYNOPSIS
       clock(3,n) option ?arg arg ...?


DESCRIPTION
       This  command  performs  one  of  several operations that may obtain or
       manipulate strings or values that represent some notion of  time.   The
       option  argument  determines what action is carried out by the command.
       The legal options (which may be abbreviated) are:

       clock(3,n) clicks ?-milliseconds?
              Return a high-resolution time(1,2,n) value as a system-dependent  inte-
              ger value.  The unit of the value is system-dependent but should
              be the highest resolution clock(3,n) available on the system such  as
              a  CPU  cycle  counter.  If -milliseconds is specified, then the
              value is guaranteed to  be  of  millisecond  granularity.   This
              value  should  only  be  used  for  the  relative measurement of
              elapsed time.

       clock(3,n) format clockValue ?-format string(3,n)? ?-gmt boolean?
              Converts an integer time(1,2,n) value, typically returned by clock(3,n) sec-
              onds,  clock(3,n)  scan, or the atime, mtime, or ctime options of the
              file(1,n) command, to human-readable form.  If the  -format  argument
              is  present the next argument is a string(3,n) that describes how the
              date and time(1,2,n) are to be formatted.  Field descriptors consist of
              a % followed by a field descriptor character.  All other charac-
              ters are copied into the result.  Valid field descriptors are:

              %%     Insert a %.

              %a     Abbreviated weekday name (Mon, Tue, etc.).

              %A     Full weekday name (Monday, Tuesday, etc.).

              %b     Abbreviated month name (Jan, Feb, etc.).

              %B     Full month name.

              %c     Locale specific date and time.  The format for  date  and
                     time(1,2,n)  in(1,8)  the default "C" locale(3,5,7) on Unix/Mac is "%a %b %d
                     %H:%M:%S %Y".  On Windows, this value is the locale(3,5,7)  spe-
                     cific  long  date  and time(1,2,n), as specified in(1,8) the Regional
                     Options control panel(1,3x,3x bottom_panel) settings.

              %C     First two digits of the four-digit year (19 or 20).

              %d     Day of month (01 - 31).

              %D     Date as %m/%d/%y.

              %e     Day of month (1 - 31), no leading zeros.

              %h     Abbreviated month name.

              %H     Hour in(1,8) 24-hour format (00 - 23).

              %I     Hour in(1,8) 12-hour format (01 - 12).

              %j     Day of year (001 - 366).

              %k     Hour in(1,8) 24-hour format, without leading zeros (0 - 23).

              %l     Hour in(1,8) 12-hour format, without leading zeros (1 - 12).

              %m     Month number (01 - 12).

              %M     Minute (00 - 59).

              %n     Insert a newline.

              %p     AM/PM indicator.

              %r     Time in(1,8) a locale-specific "meridian" format.  The "merid-
                     ian" format in(1,8) the default "C" locale(3,5,7) is "%I:%M:%S %p".

              %R     Time as %H:%M.

              %s     Count  of seconds since the epoch, expressed as a decimal
                     integer.

              %S     Seconds (00 - 59).

              %t     Insert a tab.

              %T     Time as %H:%M:%S.

              %u     Weekday number (Monday = 1, Sunday = 7).

              %U     Week of year (00 - 52), Sunday is the first  day  of  the
                     week.

              %V     Week  of  year  according to ISO-8601 rules.  Week 1 of a
                     given year is the week containing 4 January.

              %w     Weekday number (Sunday = 0, Saturday = 6).

              %W     Week of year (00 - 52), Monday is the first  day  of  the
                     week.

              %x     Locale  specific  date  format.  The format for a date in(1,8)
                     the default "C" locale(3,5,7) for Unix/Mac  is  "%m/%d/%y".   On
                     Windows,  this  value  is  the locale(3,5,7) specific short date
                     format, as specified  in(1,8)  the  Regional  Options  control
                     panel(1,3x,3x bottom_panel) settings.

              %X     Locale  specific  24-hour  time(1,2,n) format.  The format for a
                     24-hour time(1,2,n) in(1,8) the default "C" locale(3,5,7)  for  Unix/Mac  is
                     "%H:%M:%S".   On  Windows,  this value is the locale(3,5,7) spe-
                     cific time(1,2,n) format, as specified in(1,8) the  Regional  Options
                     control panel(1,3x,3x bottom_panel) settings.

              %y     Year without century (00 - 99).

              %Y     Year with century (e.g. 1990)

              %Z     Time zone name.

              If  the -format argument is not specified, the format string(3,n) "%a
              %b %d %H:%M:%S %Z %Y" is used.  If the -gmt argument is  present
              the next argument must be a boolean which if(3,n) true specifies that
              the time(1,2,n) will be formatted as Greenwich Mean Time. If false then
              the  local  timezone  will  be  used as defined by the operating
              environment.

       clock(3,n) scan dateString ?-base clockVal? ?-gmt boolean?
              Convert dateString to an integer clock(3,n)  value  (see  clock(3,n)  sec-
              onds).   This  command can parse and convert virtually any stan-
              dard date and/or time(1,2,n) string(3,n), which can  include  standard  time(1,2,n)
              zone  mnemonics.   If only a time(1,2,n) is specified, the current date
              is assumed.   If  the  string(3,n)  does  not  contain  a  time(1,2,n)  zone
              mnemonic,  the local time(1,2,n) zone is assumed, unless the -gmt argu-
              ment is true, in(1,8) which case the clock(3,n) value is calculated assum-
              ing  that the specified time(1,2,n) is relative to Greenwich Mean Time.
              -gmt, if(3,n) specified, affects only the  computed  time(1,2,n)  value;  it
              does not impact the interpretation of -base.

              If the -base flag is specified, the next argument should contain
              an integer clock(3,n) value.  Only the date in(1,8) this  value  is  used,
              not the time.  This is useful for determining the time(1,2,n) on a spe-
              cific day or doing other date-relative conversions.

              The dateString consists of zero or more  specifications  of  the
              following form:

              time(1,2,n)   A  time(1,2,n)  of  day,  which  is  of  the  form: hh?:mm?:ss??
                     ?meridian? ?zone?  or  hhmm  ?meridian?   ?zone?.  If  no
                     meridian  is  specified,  hh  is interpreted on a 24-hour
                     clock.

              date   A specific month and day with optional year.  The accept-
                     able formats are mm/dd?/yy?, monthname dd ?, yy?, dd mon-
                     thname ?yy?, day, dd monthname yy, ?CC?yymmdd, ?CC?yy-mm-
                     dd, dd-monthname-?CC?yy.  The default year is the current
                     year.  If the year is less(1,3) than 100, we treat  the  years
                     00-68 as 2000-2068 and the years 69-99 as 1969-1999.  Not
                     all platforms can represent the years 38-70, so an  error(8,n)
                     may result if(3,n) these years are used.

              ISO 8601 point-in-time
                     An ISO 8601 point-in-time specification, such as CCyymmd-
                     dThhmmss, where T is the literal T, CCyymmdd  hhmmss,  or
                     CCyymmddThh:mm:ss.

              relative time(1,2,n)
                     A specification relative to the current time.  The format
                     is number unit  acceptable  units(1,7)  are  year,  fortnight,
                     month,  week,  day, hour, minute (or min), and second (or
                     sec).  The unit can be specified as a singular or plural,
                     as  in(1,8)  3  weeks.  These modifiers may also be specified:
                     tomorrow, yesterday, today, now, last, this, next, ago.

              The actual date is calculated according to the following  steps.
              First, any absolute date and/or time(1,2,n) is processed and converted.
              Using that time(1,2,n) as  the  base,  day-of-week  specifications  are
              added.   Next,  relative  specifications are used.  If a date or
              day is specified, and no absolute or  relative  time(1,2,n)  is  given,
              midnight  is used.  Finally, a correction is applied so that the
              correct hour of the day is produced after allowing for  daylight
              savings  time(1,2,n)  differences  and  the  correct date is given when
              going from the end of a long month to a short month.

              Daylight savings time(1,2,n) correction is applied only when the  rela-
              tive  time(1,2,n)  is  specified  in(1,8)  units(1,7)  of days or more, ie, days,
              weeks, fortnights, months or years.  This means that when cross-
              ing  the  daylight savings time(1,2,n) boundary, different results will
              be given for clock(3,n) scan "1 day" and clock(3,n)  scan  "24  hours":  %
              clock(3,n)  scan  "1  day"  -base [clock(3,n) scan 1999-10-31] 941443200 %
              clock(3,n) scan "24 hours" -base [clock(3,n) scan 1999-10-31] 941439600

       clock(3,n) seconds
              Return the current date and time(1,2,n) as a  system-dependent  integer
              value.  The unit of the value is seconds, allowing it to be used
              for relative time(1,2,n) calculations.  The value is usually defined as
              total  elapsed time(1,2,n) from an ``epoch''.  You shouldn't assume the
              value of the epoch.


SEE ALSO
       date(1), time(1,2,n)(n)


KEYWORDS
       clock(3,n), date, time(1,2,n)



Tcl                                   8.4                             clock(3,n)(n)

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