When applications need to do more than mere calculations (e.g. writing a message or file), they need syscalls or system calls. This talk will give an introduction on the what/why/how applications call into the kernel, look at some illustrative examples and the interesting possibilities to make this interaction visible using strace.

This is intended to be an English version of a presentation given in German last year, with slides at https://www.zq1.de/~bernhard/doc/2015CLT/syscalls.pdf and audio recordings at https://www.zq1.de/~bernhard/doc/2015CLT/so_v3_3.ogg