Global and environmental variables

You can define global variables in the configuration file. Global variables are actually name-value pairs. When syslog-ng processes the configuration file during startup, it automatically replaces name with value. To define a global variable, use the following syntax:

   @define name "value"

The value can be any string, but special characters must be escaped (for details, see Regular expressions). To use the variable, insert the name of the variable enclosed between backticks (`, similarly to using variables in Linux or UNIX shells) anywhere in the configuration file. If backticks are meant literally, repeat the backticks to escape them. For example:

``not-substituted-value``

The value of the global variable can be also specified using the following methods:

• Without any quotes, as long as the value does not contain any spaces or special characters. In other words, it contains only the following characters: a-zA-Z0-9_..

• Between apostrophes, in case the value does not contain apostrophes.

• Between double quotes, in which case special characters must be escaped using backslashes (\\).

Example: Using global variables

For example, if an application is creating multiple log files in a directory, you can store the path in a global variable, and use it in your source definitions.

   @define mypath "/opt/myapp/logs"
    source s_myapp_1 {
        file("`mypath`/access.log" follow-freq(1));
    };
    source s_myapp_2 {
        file("`mypath`/error.log" follow-freq(1));
    };
    source s_myapp_3 {
        file("`mypath`/debug.log" follow-freq(1));
    };

The AxoSyslog application will interpret this as:

   @define mypath "/opt/myapp/logs"
    source s_myapp_1 {
        file("/opt/myapp/logs/access.log" follow-freq(1));
    };
    source s_myapp_2 {
        file("/opt/myapp/logs/error.log" follow-freq(1));
    };
    source s_myapp_3 {
        file("/opt/myapp/logs/debug.log" follow-freq(1));
    };