Week 1.docx

**Week 1** **Operating System(OS)** - **is a software that runs on a computational device , and besides a Kernel, commonly includes a set of applications for common tasks.** - **its job is to manage the computer hardware so that multiple programs can use it. Example of hardware that n...

**Week 1** **Operating System(OS)** - **is a software that runs on a computational device , and besides a Kernel, commonly includes a set of applications for common tasks.** - **its job is to manage the computer hardware so that multiple programs can use it. Example of hardware that needs managing include memory, CPU, and peripherals.** **Unix** - **an operating system developed by researchers in Bell Labs at the 1970s.** - **Allowed several users to share selected parts of a project, while keeping others private.** - **Its source code is proprietary and was licensed to universities, where the computer science students who used it, helped it make its way into the industry** **Linux** - **is a Unix-like OS originally developed by Linus Torvalds** - **it is a free OS** - **Linus made it available for other, so they are free to study it, improve it and redistribute it. GOAT!!** - **an open source so anyone can run, study, modify and redistribute.** ***Why Linux?*** - **The Linux OS and its derivatives are found in very high-profile. places such as Android phones, Google, Facebook, and the NYSE.** **GNU (Gnu's Not Unix) \[GNU pronounced as Gnoos\]** - **a modern rewrite of the Unix operating system and utilities from the 1970s.** - **is a *free software foundation* (FSF) project** - **rewrote the Unix OS as free software** - **The chief GNU architect was Richard Stallman (original author of EMACS)** - The GNU O/S kernel, name HURD, hasn't progressed very far *LINUX distribution is a Linux Kernel bundled with GNU Utilities* **Virtual Machine** - The modern fast computers are able to have a "computer" running with selected hardware specifications in your computer - Host machine is the real one, physical machine. The guest is the virtual machine - Emulation is used when the hardware required to run the guest operating system doesn't exist on the host. It is much more resource intensive as well. - Virtualization allows existing hardware for both the actual computer and the virtual one, if the hardware sufficiently matches, and most computation takes place on the actual CPU of the host **Learning Linux on a Virtual Machine** **Advantages of Using a Virtual Machine for Learning** - Running and switching between OS seamlessly, without restart - Easy to create and remove OS installations - Safe environment for making mistakes: quickly backup and restore your VM state using Snapshots - ***Snapshots --*** A feature that allows you to save the current state of the virtual machine. It is like a checkpoint. **\ ** **Shell Basics** **Typing Command Lines** - The format typically documentation or assignments involves command lines preceded by \$ symbol - Each command line begins with \$ symbol, indicating the shell prompt. - The shell prompt is not typed: it's a convention to indicate where the command should enter - **The actual output of the command, if included, is not preceded by the shell prompt.** - **The output is shown after the command line example, demonstrating the result of executing the command.** **What is a shell for?** - **The function of a shell is to find and run programs.** - **Programs are also called processes, commands, or utilities.)** - **A shell is itself a program that finds and runs other programs.** - **Shell do not do mathematics very well that's why programming is an aid to find and running of programs.** - **Command names typed into shells almost always resolve to be the names of executable files stored in system directories.** **How does the shell find and run commands** - **Shell use the \$PATH environment variable to locate executable files.** - **They offer efficient ways to edit command lines, enabling quick modifications.** - **Shells facilitate command and filename completion for faster input.** - **A built-in history feature recalls and edits previous commands, saving time**. - Use the **n** key to repeat a search if the first result isn't what you're looking for. Pressing **n** again moves to the next occurance. **Using the man command** - To access manual pages, use sngle command names or topics as arguments to the man command ex: - Ex. **\$ man date, \$ man ls, \$ man intro, \$man man.** - For a useful start page and command introduction, use **\`man intro\`.** - The introduction covers important topics such as - The shell - Pathnames and the current directory - Directories - Getting information - To find out what the -p option to the mkdir command does, use the man page for mkdir. - Type **\$ man mkdir.** - You cannot use syntax **man mkdir -p** or **man -p**. You must open the man page for mkdir and perform a text search for the -p option - Inside the mkdir man page, use the slash(**/**) character to inititate a text search for the option name (-p), and use **n** to search for subsequent occurences.