> For the complete documentation index, see [llms.txt](https://richardweiyang-2.gitbook.io/systemtap_with_examples/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://richardweiyang-2.gitbook.io/systemtap_with_examples/language/predefined_functions.md).

# Predefined Functions

systemtap provides many helpful predefined functions, like

* printf()
* print\_backtrace()
* pp()
* execname()
* task\_cpu()
* pid(), etc.

They are defined in /usr/share/systemtap/tapset. This is not only a "lib", but also a very good learning material.

[Predefinded Functions](https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/5/html/systemtap_language_reference/predefined-functions) is a good reference for those functions.