Bài giảng Hệ điều hành - Chapter 10: Case Study 1: UNIX and LINUX

Case Study 1: UNIX and LINUX Chapter 10 10.1 History of unix 10.2 Overview of unix 10.3 Processes in unix 10.4 Memory management in unix 10.5 Input/output in unix 10.6 The unix file system 10.7 Security in unix UNIX The layers of a UNIX system. UserInterface UNIX Utility Programs A few of the more common UNIX utility programs required by POSIX UNIX Kernel Approximate structure of generic UNIX kernel Processes in UNIX Process creation in UNIX. POSIX The signals required by POSIX. System Calls for Process Management s is an error code pid is a process ID residual is the remaining time from the previous alarm POSIX Shell A highly simplified shell Threads in POSIX The principal POSIX thread calls. The ls Command Steps in executing the command ls type to the shell Flags for Linux clone Bits in the sharing_flags bitmap UNIX Scheduler The UNIX scheduler is based on a multilevel queue structure Booting UNIX The sequences of processes used to boot some systems cp Handling Memory Process A's virtual address space Physical memory Process B's virtual address space Process A Process B Sharing Files Two processes can share a mapped file. A new file mapped simultaneously into two processes System Calls for Memory Management s is an error code b and addr are memory addresses len is a length prot controls protection flags are miscellaneous bits fd is a file descriptor offset is a file offset Paging in UNIX The core map in 4BSD. The core map has an entry for each page Paging in Linux (1) Linux uses three-level page tables Paging in Linux (2) Operation of the buddy algorithm. Buddy algorithm Networking Use of sockets for networking Terminal Management The main POSIX calls for managing the terminal UNIX I/O (1) Some of the fields of a typical cdevsw table UNIX I/O (2) The UNIX I/O system in BSD Streams An example of streams in System V The UNIX File System (1) Some important directories found in most UNIX systems The UNIX File System (2) Before linking. After linking. (a) Before linking. (b) After linking The UNIX File System (3) Separate file systems After mounting (a) (b) (a) Before mounting. (b) After mounting Locking Files (a) File with one lock (b) Addition of a second lock (c) A third lock System Calls for File Management s is an error code fd is a file descriptor position is a file offset The lstat System Call Fields returned by the lstat system call. System Calls for Directory Management s is an error code dir identifies a directory stream dirent is a directory entry UNIX File System (1) Disk layout in classical UNIX systems UNIX File System (2) Directory entry fields. Structure of the i-node UNIX File System (3) The relation between the file descriptor table, the open file description UNIX File System (4) A BSD directory with three files The same directory after the file voluminous has been removed The Linux File System Layout of the Linux Ex2 file system. Network File System (1) Examples of remote mounted file systems Directories are shown as squares, files as circles Network File System (2) The NFS layer structure. The NFS layer structure Security in UNIX Some examples of file protection modes System Calls for File Protection s is an error code uid and gid are the UID and GID, respectively