Apache: The Definitive Guide, 3rd Edition

Name

ExpiresByType

Synopsis

ExpiresByType mime-type time
Anywhere, .htaccess when AllowOverride Indexes

ExpiresByType takes two arguments. mime-type specifies a MIME type of file; time specifies how long these files are to remain active. There are two versions of the syntax. The first is this:

                  code 
                  seconds

There is no space between code and seconds. code is one of the following:

A

Access time (or now, in other words)

M

Last modification time of the file

seconds is simply a number. For example:

A565656

specifies 565,656 seconds after the access time.

The more readable second format is:

                  base [plus] number 
                  type [number 
                  type ...]

where base is one of the following:

access

Access time

now

Synonym for access

modification

Last modification time of the file

The plus keyword is optional, and type is one of the following:

years

months

weeks

days

hours

minutes

seconds

For example:

now plus 1 day 4 hours

does what it says.