27.13.2. How to adjust server time

In some cases, perhaps due a misconfiguration of your server, the time shown up in the News stories is wrong. Normally, it should be possible to control it by changing the time settings in either the Preferences of the administration panel, or the user preferences (Figure 27-13). However, there will be situations where a quick fix is desirable.

You can offset the time by tweaking the following line in the mainfile.php in the function formatTimeStamp (see How to adjust server time in PHP-Nuke):

$datetime = strftime(""._DATESTRING."", mktime($datetime[4],$datetime[5],$datetime[6],
$datetime[2],$datetime[3],$datetime[1]));

For example to add one hour (3600 seconds), you would simply add 3600:

$datetime = strftime(""._DATESTRING."", mktime($datetime[4],$datetime[5],$datetime[6],
$datetime[2],$datetime[3],$datetime[1]) + 3600);

or, to subtract two hours:

$datetime = strftime(""._DATESTRING."", mktime($datetime[4],$datetime[5],$datetime[6],
$datetime[2],$datetime[3],$datetime[1]) - 7200);

A situation that calls for server time modification arises when your server is located in a different timezone than your geographic location - say you are located in Japan, but your hosting company is in Canada (see How to adjust server time in PHP-Nuke). The article on phpbuilder.com On User-Defined Timezones in PHP explains the problem in detail. Quoting:

PHP's 'mktime' and 'date' functions work well as a pair without the help of any other timestamp manipulation routines, but only if the application in which they are used is concerned solely with display and entry of time in the servers timezone. If an application needs to handle entry from a timezone other than that in which the server is located something more than 'mktime' and 'date' is required.

Two things are required to accomplish this: a location independent format for storing time in the database, and methods to translate to and from that format into the user's local time.

Read the original article for a solution. To apply it to PHP-Nuke, you would need to replace the time functions with the new ones, read the time offset from the user's profile and display the result.

To reflect the new time zone that may be implied by the hardcoded time offset, you would also want to change the _DATESTRING definition in your language file, e.g. language/lang-english.php:

define("_DATESTRING","%A, %B %d @ %T %Z");

You can change the "%A, %B %d @ %T %Z" string to whatever you deem appropriate. PHP gives to some placeholders a special meaning:

• %a - abbreviated weekday name according to the current locale

• %A - full weekday name according to the current locale

• %b - abbreviated month name according to the current locale

• %B - full month name according to the current locale

• %c - preferred date and time representation for the current locale

• %C - century number (the year divided by 100 and truncated to an integer, range 00 to 99)

• %d - day of the month as a decimal number (range 01 to 31)

• %D - same as %m/%d/%y

• %e - day of the month as a decimal number, a single digit is preceded by a space (range ' 1' to '31')

• %g - like %G, but without the century.

• %G - The 4-digit year corresponding to the ISO week number (see %V). This has the same format and value as %Y, except that if the ISO week number belongs to the previous or next year, that year is used instead.

• %h - same as %b

• %H - hour as a decimal number using a 24-hour clock (range 00 to 23)

• %I - hour as a decimal number using a 12-hour clock (range 01 to 12)

• %j - day of the year as a decimal number (range 001 to 366)

• %m - month as a decimal number (range 01 to 12)

• %M - minute as a decimal number

• %n - newline character

• %p - either `am' or `pm' according to the given time value, or the corresponding strings for the current locale

• %r - time in a.m. and p.m. notation

• %R - time in 24 hour notation

• %S - second as a decimal number

• %t - tab character

• %T - current time, equal to %H:%M:%S

• %u - weekday as a decimal number [1,7], with 1 representing Monday

• %U - week number of the current year as a decimal number, starting with the first Sunday as the first day of the first week

• %V - The ISO 8601:1988 week number of the current year as a decimal number, range 01 to 53, where week 1 is the first week that has at least 4 days in the current year, and with Monday as the first day of the week. (Use %G or %g for the year component that corresponds to the week number for the specified timestamp.)

• %W - week number of the current year as a decimal number, starting with the first Monday as the first day of the first week

• %w - day of the week as a decimal, Sunday being 0

• %x - preferred date representation for the current locale without the time

• %X - preferred time representation for the current locale without the date

• %y - year as a decimal number without a century (range 00 to 99)

• %Y - year as a decimal number including the century

• %Z - time zone or name or abbreviation

• %% - a literal `%' character

You can combine them with punctuation or extra words to construct the datetime string of your liking. You are not limited to the above interpretation. For example, you can just delete the %Z, and replace it with EST or whatever you time zone is (if you cannot set it from the preferences, that is). There are some points to bear in mind while experimenting:

• Given a 'bare number' in seconds, e.g. 143567, strftime() will format this number according to your local timezone. Thus, for Germany, you will get an extra hour, since CET is GMT +1. If you are interested in simply formatting a number to give you hours, minutes and seconds (very quick for showing time values), then you should always use 'gmstrftime' instead, which will not adjust the time for your local timezone. You set the local timezone in the preferences section of the administration panel, or the preferences in the user info panel. Valid timezone codes can (usually) be seen (on Linux, at least) in /usr/share/zoneinfo or /usr/lib/zoneinfo (according to the tzset manpage).

• The call to mktime

  mktime($datetime[4],$datetime[5],$datetime[6],$datetime[2],$datetime[3],$datetime[1])

  means something equivalent to

  mktime($hour,$minute,$second,$month,$day,$year)

  assuming that $hour, $minute etc. are filled with the right values (this is exactly what the datetime array does for us).

See the PHP manual page for strftime for more information and examples about date string formatting.