Version comparisons are made by comparing the integers from left to right. If the leftmost integers are not equal, the string with the greater integer is the greater, and therefore more recent version. If the leftmost integers are equal, the comparison proceeds to the next integer, in order, from left to right, to determine the result. All unspecified integers in a version string are interpreted as having the value zero during a version comparison.

The DTrace version strings correspond to the standard nomenclature for interface versions. A change in the D programming interface is accompanied by a new version string. The following table summarizes the version strings that are used by DTrace and the likely significance of the corresponding DTrace software release.

In general, each new version of the D programming interface provides a superset of the capabilities that are offered by the previous version, with the exception of any obsolete interfaces that have been removed.

By default, any D programs that you compile by using the dtrace -s command or that you specify by using the dtrace -P, -m, -f, -n, or -i command options, are bound to the most recent D programming interface version offered by the D compiler.

You can determine the current D programming interface version by using the -V option:

# dtrace -V
dtrace: Sun D 1.6.4

# dtrace -Vv
dtrace: Sun D 1.6.4
This is DTrace 1.0.4.
dtrace(1) version-control ID: 364a014be59b349d6222991d651d38422f170e7e
libdtrace version-control ID: 364a014be59b349d6222991d651d38422f170e7e

If you want to establish a binding to a specific version of the D programming interface, you can set the version option to an appropriate version string. Similar to other DTrace options that are described in Options and Tunables, you can set the version option as follows:

# dtrace -x version=1.6 -n 'BEGIN{trace("hello");}'

Alternatively, you can use the #pragma D option syntax to set the option in your D program source file, for example:

#pragma D option version=1.6

BEGIN
{
  trace("hello");
}

If you use the #pragma D option syntax to request a version binding, you must place this directive at the top of your D program file, prior to any other declarations and probe clauses. If the version binding argument is not a valid version string or refers to a version that is not offered by the D compiler, an appropriate error message is produced and compilation fails. You can also use the version binding facility to cause the execution of a D script on an older version of DTrace to fail with an obvious error message.

Before compiling your program declarations and clauses, the D compiler loads the set of D types, functions, constants, and translators for the appropriate interface version into the compiler namespaces. Therefore, any version binding options that you specify simply control the set of identifiers, types, and translators that are visible to your program, in addition to the variables, types, and translators that your program defines. Version binding prevents the D compiler from loading newer interfaces that might define identifiers or translators that conflict with declarations in your program source code and would therefore cause a compilation error. See Identifier Names and Keywords for tips on selecting identifier names that are unlikely to conflict with interfaces offered by future versions of DTrace.

Unlike interfaces that are offered by the D compiler, interfaces that are offered by DTrace providers, that is, probes and probe arguments, are not affected by or associated with the D programming interface or the version binding options previously described. The available provider interfaces are established as part of loading your compiled instrumentation into the DTrace software in the operating system kernel. These interfaces vary, depending on the following: your instruction set architecture, operating platform, processor, the software that is installed on your Oracle Linux system, and your current security privileges. The D compiler and DTrace runtime examine the probes that are described in your D program clauses and report appropriate error messages whenever probes requested by your D program are not available. These features are orthogonal to the D programming interface version because DTrace providers do not export interfaces that can conflict with definitions in your D programs, which means you can only enable probes in D; you cannot define them. Also, probe names are kept in a separate namespace from other D program identifiers.

Use the dtrace -l command, optionally adding the -v option, to explore the set of providers and probes that are available on your Oracle Linux system. See DTrace Providers for more information about common providers and probes.