fork(), child virtual address space points to read-only parent pages. Parent and child only copies the page when there is a write (which causes a protection fault).
mmap()in Unix. Binds a file to a virtual memory region. Load into memory when a file segment is accessed. Writes back when a page is evicted.
malloc()move heap (program break) up by some size using
sbrk(). But it is tricky to return memory to the system because we might not be freeing the last object. In reality we use
outinstructions on x86. Read and write device interface registers.
..provided by the FS.
*provided by the shell program.
ln. File not removed until all synonyms are removed. Inode of the file keeps a reference count.
ln -s. File may even not exist at all. Reference count unchanged.