Introduction to Unix

Unix (Thompson and Ritchie 1974, 1978) is a general purpose operating system. It was developed by Ken Thompson and Dennis Ritchie on the PDP-11 minicomputers at Bell Labs in the early 70s. In 1975, Bell Labs released Unix to the general public. Initial recipients of this Unix system were mostly universities and non-profit institutions. It [ [ ...]

Introduction to Linux

1. Introduction to Linux Linux (Linux 2017) is a Unix-like system. It started as an experimental kernel for the Intel x86 based PCs by Linus Torvalds in 1991. Subsequently, it was developed by a group of people world-wide. A big milestone of Linux occurred in the late 90s when it combined with GNU (Stallman 2017) [ [ ...]

Use Ubuntu Linux

1. Ubuntu Versions Among the different versions of Linux, we recommend Ubuntu Linux 15.10 or later for the following reasons. It is very easy to install. It can be installed online if the user has connection to the Internet. It is very easy to install additional software packages by sudo apt-get install PACKAGE It is [ [ ...]

Unix/Linux File System Organization

The Unix/Linux file system is organized as a tree, which is shown (sideway) in Fig. 1.6. Unix/Linux considers everything that can store or provide information as a file. In a general sense, each node of the file system tree is a FILE. In Unix/Linux, files have the following types. 1. File Types Directory files: A [ [ ...]

Ubuntu Linux System Administration

1. User Accounts As in all Linux, user accounts are maintained in the /etc/passwd file, which is owned by the superuser but readable by anyone. Each user has a line in the /etc/passwd file of the form loginName:x:gid:uid:usefInfo:homeDir:initialProgram where the second field x indicates checking user password. Encrypted user passwords are maintained in the /etc/shadow [ [ ...]

Using Text Editors in Linux

1. Text Editors in Linux 1.1. Vim Vim (Linux Vi and Vim Editor 2017) is the standard built-in editor of Linux. It is an improved version of the original default Vi editor of Unix. Unlike most other editors, vim has 3 different operating modes, which are . Command mode: for entering commands . Insert mode: [ [ ...]

Program Development with Unix/Linux

1. Program Development Steps The steps of developing an executable program are as follows. (1). Create source files: Use a text editor, such as gedit or emacs, to create one or more source files of a program. In systems programming, the most important programming languages are C and assembly. We begin with C programs first. [ [ ...]

Function Call in C in Unix/Linux

Next, we consider the run-time behavior of a.out during execution. The run-time behavior of a program stems mainly from function calls. The following discussions apply to running C programs on 32-bit Intel x86 processors. On these machines, the C compiler generated code passes parameters on the stack in function calls. During execution, it uses a [ [ ...]

Link C Program with Assembly Code in Unix/Linux

In systems programming, it is often necessary to access and control the hardware, such as CPU registers and I/O port locations, etc. In these situations, assembly code becomes necessary. It is therefore important to know how to link C programs with assembly code. 1. Programming in Assembly  C code to Assembly Code /************* a c [ [ ...]

Link Library in Unix/Linux

A link library contains precompiled object code. During linking, the linker uses the link library to complete the linking process. In Linux, there are two kinds of link libraries; static link library for static linking, and dynamic link library for dynamic linking. In this section, we show how to create and use link libraries in [ [ ...]

Makefile in Unix/Linux

So far, we have used individual gcc commands to compile-link the source files of C programs. For convenience, we may also use a sh script which includes all the commands. These schemes have a major drawback. If we only change a few of the source files, the sh commands or script would still compile all [ [ ...]

The GDB Debugger in Unix/Linux

The GNU Debugger (GDB) (Debugging with GDB 2002; GDB 2017) is an interactive debugger, which can debug programs written in C, C++ and several other languages. In Linux, the command man gdb displays the manual pages of gdb, which provides a brief description of how to use GDB. The reader may find more detailed information [ [ ...]

Structures in C in Unix/Linux

A structure is a composite data type containing a collection of variables or data objects. Structure types in C are defined by the struct keyword. Assume that we need a node structure containing the following fields. next : a pointer to the next node structure; key : an integer; name : an array of 64 [ [ ...]

Link List Processing in Unix/Linux

Structures and pointers are often used to construct and manipulate dynamic data structures, such as link lists, queues and trees, etc. The most basic type of dynamic data structures is the link list. In this section, we shall explain the concepts of link list, list operations, and demonstrate list processing by example programs. 1. Link [ [ ...]

Trees in Unix/Linux

1. Trees A tree is a dynamic data structure composed of multi-levels of linked lists. As a data structure, a tree is defined as a node, which itself consists of a value together with a list of references to other nodes. Symbolically, a tree is defined recursively as node: value [&node[1], …, &node[k]] where each [ [ ...]

Programming Project: Unix/Linux File System Tree Simulator

Summarizing the background information on C structures, link list processing and binary trees, we are ready to integrate these concepts and techniques into a programming project to solve a practical problem. The programming project is to design and implement a Unix/Linux file system tree simulator. 1. Unix/Linux File System Tree The logical organization of a [ [ ...]

Process Management in Unix/Linux: A Multitasking System

1. Multitasking In general, multitasking refers to the ability of performing several independent activities at the same time. For example, we often see people talking on their cell phones while driving. In a sense, these people are doing multitasking, although a very bad kind. In computing, multitasking refers to the execution of several independent tasks [ [ ...]

Process Management in Unix/Linux: Process Synchronization

An operating system comprises many concurrent processes, which may interact with one another. Process synchronization refers to the rules and mechanisms used to control and coordinate process interactions to ensure their proper executions. The simplest tools for process synchronization are sleep and wakeup operations. 1. Sleep Operation Whenever a process needs something, e.g. a memory [ [ ...]

Process Management in Unix/Linux: Process Termination

In an operating system, a process may terminate or die, which is a common term of process termina­tion. As mentioned in Chap. 2, a process may terminate in two possible ways: Normal termination: The process calls exit(value), which issues _exit(value) system call to execute kexit(value) in the OS kernel, which is the case we are [ [ ...]

Process Management in the MT Multitasking System

This section presents a programming exercise for the reader to refine the base MT system to implement process management functions for the MT system. Specifically,  Implement process family tree as a binary tree.  Implement ksleep() and kwakeup() for process synchronization.  Implement kexit() and kwait() for process management.  Add a ‘w’ command to test and demonstrate [ [ ...]