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97 lines
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<!Converted with LaTeX2HTML 95.1 (Fri Jan 20 1995) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds >
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<TITLE>3.9.2 Interpreting file permissions</TITLE>
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<BR> <HR><A NAME=tex2html3352 HREF="node127.html"><IMG ALIGN=BOTTOM ALT="next" SRC="next_motif.gif"></A> <A NAME=tex2html3350 HREF="node124.html"><IMG ALIGN=BOTTOM ALT="up" SRC="up_motif.gif"></A> <A NAME=tex2html3344 HREF="node125.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="previous_motif.gif"></A> <A NAME=tex2html3354 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <A NAME=tex2html3355 HREF="node250.html"><IMG ALIGN=BOTTOM ALT="index" SRC="index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html3353 HREF="node127.html">3.9.3 Dependencies</A>
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<B>Up:</B> <A NAME=tex2html3351 HREF="node124.html">3.9 File Permissions</A>
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<B> Previous:</B> <A NAME=tex2html3345 HREF="node125.html">3.9.1 Concepts of file </A>
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<BR> <HR> <P>
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<H2><A NAME=SECTION00592000000000000000>3.9.2 Interpreting file permissions</A></H2>
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<P>
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<A NAME=3200> </A>
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<A NAME=3201> </A>
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<A NAME=3283> </A>
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<A NAME=3284> </A>
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Let's look at an example to demonstrate file permissions. Using the
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<tt>ls</tt> command with the <tt>-l</tt> option will display a ``long''
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listing of the file, including file permissions.
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<P><TT> /home/larry/foo# <em>ls -l stuff</em>
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<PRE>-rw-r--r-- 1 larry users 505 Mar 13 19:05 stuff
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</PRE>
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/home/larry/foo#
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<P></TT>
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<P>
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The first field printed in the listing represents the file permissions.
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The third field is the owner of the file (<tt>larry</tt>), and the fourth
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field is the group to which the file belongs (<tt>users</tt>). Obviously,
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the last field is the name of the file (<tt>stuff</tt>), and we'll cover the
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other fields later.
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<P>
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This file is owned by <tt>larry</tt>, and belongs to the group <tt>users</tt>.
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Let's look at the file permissions. The string <tt>-rw-r--r--</tt> lists,
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in order, the permissions granted to the file's owner, the file's group,
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and everybody else.
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<P>
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The first character of the permissions string (``<tt>-</tt>'') represents the
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type of file. A ``<tt>-</tt>'' just means that this is a regular file (as
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opposed to a directory or device driver). The next three letters
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(``<tt>rw-</tt>'') represent the permissions granted to the file's owner,
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<tt>larry</tt>. The ``<tt>r</tt>'' stands for ``read'' and the ``<tt>w</tt>''
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stands for ``write''. Thus, <tt>larry</tt> has read and write permission
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to the file <tt>stuff</tt>.
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<P>
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As we mentioned, besides read and write permission, there is also
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``execute'' permission---represented by an ``<tt>x</tt>''. However, there
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is a ``<tt>-</tt>'' here in place of the ``<tt>x</tt>'', so Larry doesn't
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have execute permission on this file. This is fine, the file <tt>stuff</tt>
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isn't a program of any kind. Of course, because Larry owns the file,
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he may grant himself execute permission for the file if he so desires.
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This will be covered shortly.
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<P>
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The next three characters, <tt>r--</tt>, represent the group's permissions
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on the file. The group which owns this file is <tt>users</tt>. Because
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only an ``<tt>r</tt>'' appears here, any user which belongs to the group
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<tt>users</tt> may read this file.
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<P>
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The last three characters, also <tt>r--</tt>, represent the permissions
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granted to every other user on the system (other than the owner of the
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file and those in the group <tt>users</tt>). Again, because only an
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``<tt>r</tt>'' is present, other users may read the file, but not write to
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it or execute it.
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<P>
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Here are some other examples of group permissions.
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<DL COMPACT><DT><tt>-rwxr-xr-x</tt>
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<DD>
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The owner of the file may
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read, write, and execute the file. Users in the file's group, and all other
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users, may read and execute the file.
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<P>
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<DT><tt>-rw-------</tt>
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<DD>
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The owner of the file may
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read and write the file. No other user can access the file.
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<P>
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<DT><tt>-rwxrwxrwx</tt>
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<DD>
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All users may read, write, and execute the file.
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<P>
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</DL><BR> <HR><A NAME=tex2html3352 HREF="node127.html"><IMG ALIGN=BOTTOM ALT="next" SRC="next_motif.gif"></A> <A NAME=tex2html3350 HREF="node124.html"><IMG ALIGN=BOTTOM ALT="up" SRC="up_motif.gif"></A> <A NAME=tex2html3344 HREF="node125.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="previous_motif.gif"></A> <A NAME=tex2html3354 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <A NAME=tex2html3355 HREF="node250.html"><IMG ALIGN=BOTTOM ALT="index" SRC="index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html3353 HREF="node127.html">3.9.3 Dependencies</A>
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<B>Up:</B> <A NAME=tex2html3351 HREF="node124.html">3.9 File Permissions</A>
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<B> Previous:</B> <A NAME=tex2html3345 HREF="node125.html">3.9.1 Concepts of file </A>
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<BR> <HR> <P>
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<BR> <HR>
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<P><ADDRESS>
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<I>Matt Welsh <BR>
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mdw@sunsite.unc.edu</I>
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</ADDRESS>
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</BODY>
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