Apache provides a convenient way to conditionally check for its version number, which can be useful when writing directives that require specific modules and configurations. This tutorial explains how it's done with a few simple examples.
Thanks to Apache's version module, mod_version, we conditionally may check Apache's current version number. This module is available in Apache 2.0.56 and later.
Currently the only directive included in
<IfVersion>, which may be included via the server configuration file, virtual host, directory, or .htaccess. So it's a pretty straightforward module to learn. Let's look at some examples of
<IfVersion> to see how it works.
Greater than or equal to a specific version of Apache:
<IfVersion >= 2.4> # do stuff for Apache greater than or equal to version 2.4.0 </IfVersion>
Less than specific Apache version:
<IfVersion < 2.3> # do stuff for Apache less than version 2.3.0 </IfVersion>
Using a regular expression to match specific version numbers:
<IfVersion = /^2.4.$/> # matches versions 2.4.0, 2.4.1, 2.4.2, 2.4.3, 2.4.4 </IfVersion>
Instead of forward-slashing the regex as in the previous example, we can replace the slashes with a tilde
<IfVersion !~ ^2.4.$> # matches any version that is NOT 2.4.0, 2.4.1, 2.4.2, 2.4.3, 2.4.4 </IfVersion>
Notice here that we are negating the regular expression by prefixing it with an exclamation point
!. Also note that if the operator is omitted, it's assumed to be "equals"
=. You can get more details in the Apache documentation.