"Interesting" System Calls (Cont.)

brk - increase the size of the program's heap (usually invoked by malloc, when it needs more virtual memory).

stat, stat64 - get information about a file (does it exist? what is its length? access permissions?)

umask - defines a set of flags that will be used to 'mask out' file permissions set for new files this process will create.

mmap - load a given file and map its contents into part of the virtual memory of an application. reading this memory will actually read from the file.

munmap - unmap a previously mmaped file.