NAME
       clock - Obtain and manipulate time

SYNOPSIS
       clock 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 clicks
              Return  a  high-resolution  time value as a system-
              dependent integer value.  The unit of the value  is
              system-dependent  but should be the highest resolu-
              tion clock available on the system such  as  a  CPU
              cycle  counter.  This value should only be used for
              the relative measurement of elapsed time.

       clock format clockValue ?-format string? ?-gmt boolean?
              Converts an integer time value, typically  returned
              by  clock seconds, clock scan, or the atime, mtime,
              or ctime options of the  file  command,  to  human-
              readable  form.  If the -format argument is present
              the next argument is a string  that  describes  how
              the  date  and  time  are  to  be formatted.  Field
              descriptors consist of a  %  followed  by  a  field
              descriptor  character.   All  other  characters 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.

              %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 (00 - 23).
              %I     Hour (00 - 12).

              %j     Day number of year (001 - 366).

              %m     Month number (01 - 12).

              %M     Minute (00 - 59).

              %n     Insert a newline.

              %p     AM or PM.

              %r     Time as %I:%M:%S %p.

              %R     Time as %H:%M.

              %S     Seconds (00 - 59).

              %t     Insert a tab.

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

              %U     Week number of year (01 - 52), Sunday is the
                     first day of the week.

              %w     Weekday number (Sunday = 0).

              %W     Week number of year (01 - 52), Monday is the
                     first day of the week.

              %x     Local specific date format.

              %X     Local specific time format.

              %y     Year within century (00 - 99).

              %Y     Year as ccyy (e.g. 1990)

              %Z     Time zone name.

              If  the -format argument is not specified, the for-
              mat string "%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 true specifies that the  time
              will  be formatted as Greenwich Mean Time. If false
              then the local timezone will be used as defined  by
              the operating environment.

       clock scan dateString ?-base clockVal? ?-gmt boolean?
              Convert  dateString  to an integer clock value (see
              clock seconds).  This command can parse and convert
              virtually  any  standard  date  and/or time string,
              which can include standard time zone mnemonics.  If
              only  a  time  is  specified,  the  current date is
              assumed.  If the string does  not  contain  a  time
              zone  mnemonic,  the  local  time  zone is assumed,
              unless the -gmt argument is true, in which case the
              clock  value is calculated assuming that the speci-
              fied time is relative to Greenwich Mean Time.

              If the -base flag is specified, the  next  argument
              should  contain  an  integer clock value.  Only the
              date in this value is used, not the time.  This  is
              useful  for  determining the time on a specific day
              or doing other date-relative conversions.

              The dateString consists of zero or more  specifica-
              tions of the following form:

              time   A  time  of  day,  which  is  of  the  form:
                     hh?:mm?:ss??   ?meridian?  ?zone?  or   hhmm
                     ?meridian?  ?zone?. If no meridian is speci-
                     fied, hh is interpreted on a 24-hour  clock.

              date   A specific month and day with optional year.
                     The acceptable formats are mm/dd?/yy?,  mon-
                     thname dd ?, yy?, dd monthname ?yy? and day,
                     dd monthname yy.  The default  year  is  the
                     current year.  If the year is less then 100,
                     then 1900 is added to it.

              relative time
                     A  specification  relative  to  the  current
                     time.   The format is number unit acceptable
                     units 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 3 weeks.  These modifiers may
                     also  be  specified:  tomorrow,   yesterday,
                     today, now, last, this, next, ago.

              The actual date is calculated according to the fol-
              lowing steps.  First, any absolute date and/or time
              is processed and converted.  Using that time 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  is
              given,  midnight is used.  Finally, a correction is
              applied so that the correct hour of the day is pro-
              duced after allowing for daylight savings time dif-
              ferences.

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


KEYWORDS
       clock, date, time
