Unix Files and Directories

<BODY LANG="EN"> <HR><center> <table border=1> <td><img height=36 width=36 alt="" src="http://www.cs.utah.edu/icons/latex2html/previous_fade.gif"></td> <td><A NAME="tex2html9" HREF="../../../classes/Unix/contents.shtml"><img height=36 width=36 alt="UP" src="http://www.cs.utah.edu/icons/latex2html/up.gif"></A></td> <td><A NAME="tex2html11" HREF="node1.shtml"><img height=36 width=36 alt="NEXT" src="http://www.cs.utah.edu/icons/latex2html/next.gif"></A></td> <td><a href="contents-unix04.shtml"><img height=36 width=36 alt="CONTENTS" src="http://www.cs.utah.edu/icons/latex2html/toc.gif"></a></td> <td>     </td> </table> </center> <HR> <P> <H1>Unix Files and Directories</H1> <P> This lesson focuses on the Unix file system, and how to manipulate files and navigate directories. We will begin by looking at basic Unix commands for manipulating files and directories. In Unix, a file can be one of three types: a text file (such as a letter or a program), an executable file (such as a compiled program), or a directory (a file ``containing'' other files). <P> When you consider that there are thousands of users of the local workstation network, you will realize that the computers must keep track of tens or hundreds of thousands of files. Unix uses directories to organize these files, much like a filing cabinet uses drawers and folders to keep track of documents. <P> The Unix file system is organized around a single structure of directories, where each directory can contain more directories (often called subdirectories) and/or files. The entire file system, often spanning many machines and disks, can be visualized as a tree. Picture this tree as growing upside down, with the root at the top and the leaves toward the bottom. The leaves are all text and executable files, while the root, trunk, limbs, branches, and twigs are all directories. <P> The file system is called the directory tree, and the directory at the base of the tree is called the root directory. Every file and directory in the file system has a unique name, called its pathname. The pathname of the root directory is <tt>/</tt>. <P> As a Unix user, you are given control over one directory. This directory is called your home directory, and it was created when your account was established. This directory is your personal domain, over which you have complete control. You are free to create your own subtree of files and directories within your home directory. To determine the pathname of your home directory, enter the following command in an XTerm window. The first part of the command makes sure that you are indeed connected to your home directory; the second command displays its name. <P> <PRE>cd; pwd</PRE> <P> Everyone has a different home directory, but two things are certain. The pathname of your home directory will start with a slash (everything is rooted in the root directory) and it will end with your user name. For example, suppose that a user jones has a home directory /home/jones. From this, we can tell that the root directory <tt>/</tt> contains a subdirectory called <tt>home</tt>, which contains a subdirectory called <tt>jones</tt>. Every directory has a pathname that shows the sequence of directories that lead from it back to the root. <P> Below, you will learn how to explore the file system at large as well as how to create directories and files inside your own small piece of it. <em>Be sure to try out the example commands as you learn about them. Otherwise, you won't learn very much.</em> <P> <HR><center> <table border=1> <td><img height=36 width=36 alt="" src="http://www.cs.utah.edu/icons/latex2html/previous_fade.gif"></td> <td><A NAME="tex2html9" HREF="../../../classes/Unix/contents.shtml"><img height=36 width=36 alt="UP" src="http://www.cs.utah.edu/icons/latex2html/up.gif"></A></td> <td><A NAME="tex2html11" HREF="node1.shtml"><img height=36 width=36 alt="NEXT" src="http://www.cs.utah.edu/icons/latex2html/next.gif"></A></td> <td><a href="contents-unix04.shtml"><img height=36 width=36 alt="CONTENTS" src="http://www.cs.utah.edu/icons/latex2html/toc.gif"></a></td> <td>     </td> </table> </center> <HR> </BODY>