CSc 352: Basic Unix presents of Layers of a Unix system; Referring to files Absolute Paths; Home directories; Input and output; Unix Commands; Combining commands; Finding out about commands I; Some other useful commands;. | CSc 352: Basic Unix Saumya Debray Dept. of Computer Science The University of Arizona, Tucson debray@ Reading Chapter 1: Upto “Background Jobs” (page 17) What is Unix? Unix is an operating system sits between the hardware and the user/applications provides high-level abstractions (., files) and services (., multiprogramming) Linux: a “Unix-like” operating system: user-level interface very similar to Unix code base is different from original Unix code Layers of a Unix system hardware shell Unix operating system kernel users applications shell commands system calls The file system A file is basically a sequence of bytes Collections of files are grouped into directories ( folders) A directory is itself a file file system has a hierarchical structure (., like a tree) the root is referred to as “/” dd cc bb / ff ee “Everything is a file” In Unix, everything looks like a file: documents stored on disk directories inter-process communication network | CSc 352: Basic Unix Saumya Debray Dept. of Computer Science The University of Arizona, Tucson debray@ Reading Chapter 1: Upto “Background Jobs” (page 17) What is Unix? Unix is an operating system sits between the hardware and the user/applications provides high-level abstractions (., files) and services (., multiprogramming) Linux: a “Unix-like” operating system: user-level interface very similar to Unix code base is different from original Unix code Layers of a Unix system hardware shell Unix operating system kernel users applications shell commands system calls The file system A file is basically a sequence of bytes Collections of files are grouped into directories ( folders) A directory is itself a file file system has a hierarchical structure (., like a tree) the root is referred to as “/” dd cc bb / ff ee “Everything is a file” In Unix, everything looks like a file: documents stored on disk directories inter-process communication network connections devices (printers, graphics cards, interactive terminals, ) They are accessed in a uniform way: consistent API (., read, write, open, close, ) consistent naming scheme (., /home/debray, /dev/cdrom) Referring to files: Absolute Paths An absolute path specifies how to get to a file starting at the file system root list the directories on the path from the root (“/”), separated by “/” dd cc bb / ff ee gg Referring to files: Absolute Paths An absolute path specifies how to get to a file starting at the file system root list the directories on the path from the root (“/”), separated by “/” dd cc bb / ff ee gg absolute path: /dd/ee/gg Referring to Files: Relative Paths Typically we have a notion of a “current directory” A relative path specifies how to get to a file starting from the current directory ‘’ means “move up one level” ‘.’ means current directory list the directories on the path separated by “/” dd cc bb / ff ee gg Referring to files: Relative
