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How to find the date of previous day in shell script?
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MKTIME(3) 1 MKTIME(3) mktime - Get Unix timestamp for a date SYNOPSIS
int mktime ([int $hour = date("H")], [int $minute = date("i")], [int $second = date("s")], [int $month = date("n")], [int $day = date("j")], [int $year = date("Y")], [int $is_dst = -1]) DESCRIPTION
Returns the Unix timestamp corresponding to the arguments given. This timestamp is a long integer containing the number of seconds between the Unix Epoch (January 1 1970 00:00:00 GMT) and the time specified. Arguments may be left out in order from right to left; any arguments thus omitted will be set to the current value according to the local date and time. NOTES
Note As of PHP 5.1, when called with no arguments, mktime(3) throws an E_STRICT notice: use the time(3) function instead. PARAMETERS
o $hour - The number of the hour relative to the start of the day determined by $month, $day and $year. Negative values reference the hour before midnight of the day in question. Values greater than 23 reference the appropriate hour in the following day(s). o $minute - The number of the minute relative to the start of the $hour. Negative values reference the minute in the previous hour. Values greater than 59 reference the appropriate minute in the following hour(s). o $second - The number of seconds relative to the start of the $minute. Negative values reference the second in the previous minute. Values greater than 59 reference the appropriate second in the following minute(s). o $month - The number of the month relative to the end of the previous year. Values 1 to 12 reference the normal calendar months of the year in question. Values less than 1 (including negative values) reference the months in the previous year in reverse order, so 0 is December, -1 is November, etc. Values greater than 12 reference the appropriate month in the following year(s). o $day - The number of the day relative to the end of the previous month. Values 1 to 28, 29, 30 or 31 (depending upon the month) refer- ence the normal days in the relevant month. Values less than 1 (including negative values) reference the days in the previous month, so 0 is the last day of the previous month, -1 is the day before that, etc. Values greater than the number of days in the relevant month reference the appropriate day in the following month(s). o $year - The number of the year, may be a two or four digit value, with values between 0-69 mapping to 2000-2069 and 70-100 to 1970-2000. On systems where time_t is a 32bit signed integer, as most common today, the valid range for $year is somewhere between 1901 and 2038. However, before PHP 5.1.0 this range was limited from 1970 to 2038 on some systems (e.g. Windows). o $is_dst - This parameter can be set to 1 if the time is during daylight savings time (DST), 0 if it is not, or -1 (the default) if it is unknown whether the time is within daylight savings time or not. If it's unknown, PHP tries to figure it out itself. This can cause unexpected (but not incorrect) results. Some times are invalid if DST is enabled on the system PHP is running on or $is_dst is set to 1. If DST is enabled in e.g. 2:00, all times between 2:00 and 3:00 are invalid and mktime(3) returns an undefined (usu- ally negative) value. Some systems (e.g. Solaris 8) enable DST at midnight so time 0:30 of the day when DST is enabled is evalu- ated as 23:30 of the previous day. Note As of PHP 5.1.0, this parameter became deprecated. As a result, the new timezone handling features should be used instead. Note This parameter has been removed in PHP 7.0.0. RETURN VALUES
mktime(3) returns the Unix timestamp of the arguments given. If the arguments are invalid, the function returns FALSE (before PHP 5.1 it returned -1). ERRORS
/EXCEPTIONS Every call to a date/time function will generate a E_NOTICE if the time zone is not valid, and/or a E_STRICT or E_WARNING message if using the system settings or the $TZ environment variable. See also date_default_timezone_set(3) CHANGELOG
+--------+---------------------------------------------------+ |Version | | | | | | | Description | | | | +--------+---------------------------------------------------+ | 7.0.0 | | | | | | | $is_dst parameter has been removed. | | | | | 5.3.0 | | | | | | | mktime(3) now throws E_DEPRECATED notice if the | | | $is_dst parameter is used. | | | | | 5.1.0 | | | | | | | The $is_dst parameter became deprecated. Made | | | the function return FALSE on error, instead of | | | -1. Fixed the function to accept the year, month | | | and day to be all passed as zero. | | | | | 5.1.0 | | | | | | | When called with no arguments, mktime(3) throws | | | E_STRICT notice. Use the time(3) function | | | instead. | | | | | 5.1.0 | | | | | | | Now issues the E_STRICT and E_NOTICE time zone | | | errors. | | | | +--------+---------------------------------------------------+ EXAMPLES
Example #1 mktime(3) basic example <?php // Set the default timezone to use. Available as of PHP 5.1 date_default_timezone_set('UTC'); // Prints: July 1, 2000 is on a Saturday echo "July 1, 2000 is on a " . date("l", mktime(0, 0, 0, 7, 1, 2000)); // Prints something like: 2006-04-05T01:02:03+00:00 echo date('c', mktime(1, 2, 3, 4, 5, 2006)); ?> Example #2 mktime(3) example mktime(3) is useful for doing date arithmetic and validation, as it will automatically calculate the correct value for out-of-range input. For example, each of the following lines produces the string "Jan-01-1998". <?php echo date("M-d-Y", mktime(0, 0, 0, 12, 32, 1997)); echo date("M-d-Y", mktime(0, 0, 0, 13, 1, 1997)); echo date("M-d-Y", mktime(0, 0, 0, 1, 1, 1998)); echo date("M-d-Y", mktime(0, 0, 0, 1, 1, 98)); ?> Example #3 Last day of a month The last day of any given month can be expressed as the "0" day of the next month, not the -1 day. Both of the following examples will produce the string "The last day in Feb 2000 is: 29". <?php $lastday = mktime(0, 0, 0, 3, 0, 2000); echo strftime("Last day in Feb 2000 is: %d", $lastday); $lastday = mktime(0, 0, 0, 4, -31, 2000); echo strftime("Last day in Feb 2000 is: %d", $lastday); ?> NOTES
Caution Before PHP 5.1.0, negative timestamps were not supported under any known version of Windows and some other systems as well. There- fore the range of valid years was limited to 1970 through 2038. SEE ALSO
checkdate(3), gmmktime(3), date(3), time(3). PHP Documentation Group MKTIME(3)
