Relative and Absolute Paths

<BODY > <HR><center> <table border=1> <td> <A NAME="tex2html27" HREF="node1.html"><img height=36 width=36 alt="PREVIOUS" src="../../../icons/latex2html/previous.gif"></A></td> <td> <A NAME="tex2html33" HREF="unix_intro.html"><img height=36 width=36 alt="UP" src="../../../icons/latex2html/up.gif"></A></td> <td> <A NAME="tex2html35" HREF="node3.html"><img height=36 width=36 alt="NEXT" src="../../../icons/latex2html/next.gif"></A></td> <td><a href="contents-node2.html"><img height=36 width=36 alt="CONTENTS" src="../../../icons/latex2html/toc.gif"></a></td> </table> </center> <HR>  <H1><A NAME="SECTION00020000000000000000"> Relative and Absolute Paths</A> </H1> <P> Unix files and directories are organized into an inverted tree with the trunk representing the root or top-level directory the branches and sub-branches representing the lower subdirectories and the leaves representing the files. Your home directory has a name something like this: <PRE> /u/class/myname </PRE> The root or toplevel directory <B>/</B> contains a subdirectory <B>u</B>, which, in turn, contains a subdirectory <B>class</B>, etc. As shown, this name gives an <EM>absolute path</EM> to your home directory. All absolute paths starti with a slash <B>/</B> for the root directory. In general the <EM>path</EM> specifies the route from the current working directory to the file or directory you wish to access. Paths are either absolute or relative. For example. suppose your current working directory is <B>/u/stu</B>. Then the <EM>relative path</EM> to your home directory would be specified by <B>p6720/myname</B>. The absolute path gets you there, regardless of where you start. The relative path depends on where you start. <P> For further examples, suppose your home directory contains subdirectories <B>asst01</B> and <B>asst02</B>. Suppose your current working directory is <PRE> /u/class/myname/asst02 </PRE> What is the relative path to your directory <B>asst01</B>? It is <B>../asst01</B>. The <B>..</B> backs up to your home directory and the <B>/asst01</B> takes you from there down to the subdirectory <B>asst01</B>. The absolute path to your directory <B>asst01</B> is given by <PRE> /u/class/myname/asst01 </PRE> A convenient shorthand uses <B>~</B> which stands for your home directory. Thus <B>~/asst01</B> is also an <EM>absolute path</EM> to the directory <B>asst01</B>. <P> A path often refers to a file as well. Thus in the example above, if the current directory is <B>asst02</B> and you want to refer to a file <B>mytext</B> located in the directory <B>asst01</B>, the relative path is <B>../asst01/mytext</B>. <P> Most shells have an environment variable <B>PATH</B>, which is actually a list of absolute paths to directories where binary executable files are to be found. <P> <HR><center> <table border=1> <td> <A NAME="tex2html27" HREF="node1.html"><img height=36 width=36 alt="PREVIOUS" src="../../../icons/latex2html/previous.gif"></A></td> <td> <A NAME="tex2html33" HREF="unix_intro.html"><img height=36 width=36 alt="UP" src="../../../icons/latex2html/up.gif"></A></td> <td> <A NAME="tex2html35" HREF="node3.html"><img height=36 width=36 alt="NEXT" src="../../../icons/latex2html/next.gif"></A></td> <td><a href="contents-node2.html"><img height=36 width=36 alt="CONTENTS" src="../../../icons/latex2html/toc.gif"></a></td> </table> </center> <HR>  <HR><P><ADDRESS> <I></I> </ADDRESS> </BODY>